Maharashtra State Board Class 7 Science Solutions Chapter 16 Natural Resources

Class 7 Science Chapter 16 Natural Resources Textbook Questions and Answers

1. Describe natural resources with reference to the following 3 types:

Question a.
Mineral resources
Answer:
Mineral wealth has an important place among natural resources. The rocks on the earth are mainly made of minerals. These minerals can be obtained by mining. Minerals that contain a high proportion of metals are ores, (i) Minerals are formed from the magma in the earth’s crust and the lava from the eruption of volcanoes when they cool and get transformed into crystals e.g. magnetite, mica, (ii) Minerals get transformed from one form into another due to large changes in temperature and pressure e.g. Diamond, Graphite, (iii) There are 3 types of minerals according to their properties Non-metal minerals: e.g. mica, sulphur, potash, diamond.

• Metals minerals: e.g. Iron, gold, silver, tin, bauxite, platinum.
• Energy minerals: e.g. Coal, mineral oil, natural gas, diamond, ruby, sapphire, jade are used as gems.

Some important minerals and ores are Iron ore, manganese, bauxite, copper and mica.

Question b.
Forest resources
Answer:

1. A forest is a natural habitat of plants, animals and microbes.
2. Forest perform certain specific protective and productive functions.
3. We get different types of wood and many medicinal plants from forests.
4. Forest wealth includes fire wood, trees like teak, mahogany, neem, acacia, subabhul, fibers, paper, rubber, gum, aromatic substances.
5. We get fragrant essential oils from lemon grass, vanilla, kewada, vetiver (khus) and eucalyptus.
6. Sandalwood and oil of eucalyptus are used for making soaps, cosmetics and incense sticks.
7. Also we get fruits, bulbs, roots, honey, sealing wax, dyes from forest.
8. Many medicinal plants adulsa, bel, neem, periwinkle, cinnamon, are used for treatment of various diseases such as cough cold, malaria, diarrhoea, cancer, fever and cold.
9. Wood is used as a source of energy for cooking purpose and for keeping warm.
10. For making furniture, tool handles, matches, bridges, boats etc.
11. Bamboos are used for matting, flooring, basket, ropes, rafts, cots etc.
12. Bamboos, wood are used in the manufacture of rayon, yams, artificial silk-fibers.

Question c.
Ocean resources
Answer:

1. Oceans occupy about 70% of a earth’s surface.
2. Energy can be obtained on a large scale from oceans.
3. Sea waves at high and low tide and ocean currents are being used for generation of power.
4. There are billions of tons of minerals dissolved in ocean water.
5. There are large reserves of tin, chromium, potassium, phosphates, copper, zinc, iron, lead, thorium, manganese, sulphur, uranium in the ocean and sea beds.
6. Also we get many types of gems, conches, shells and pearls from the sea.
7. There are large reserves of mineral oil and natural gas at the bottom of sea.
8. We get fishes, dried shrimp, shells, fungi, shark, cod fish and sea cucumber from the ocean.

2. Write answers to the following questions in your own words.

Question a.
What is meant by fossil fuel? What are their types?
Answer:

1. Fossil fuels (such as coal or natural gas) are formed in the earth from dead plants and animals, due to high pressure from above and the heat from the earth’s interior.
2. The dead plants, animals get transformed into fossil fuel.
3. There are three types of fossil fuels which can be used for energy production, Coal, oil and natural gas.

a. Coal:

1. Coal is a solid fossil fuel formed over millions of years by the decay of land vegetation,
2. Coal is a store house of carbon. Coal is found in mines,
3. It is like porous, hard, black rock.
4. It is burnt to obtain heat energy.
5. It is used as a fuel in thermal power plants and to run boilers and railway engines, for cooking and baking bricks.
6. Anthracite is the coal of the highest grade.
7. Producer gas and water gas are obtained from coal.

b. Mineral oil:

1. Mineral oil is the liquid fuel formed by the decomposition of organic substances buried underground,
2. The underground mineral oil is extracted through oil wells.
3. Mineral oil is found mainly in oil sands, shale, sandstone and limestone at a depth of about 1000 to 3000 metres.
4. Mineral oil is also known as petroleum or crude oil. It is greenish-brown in colour.
5. Petroleum is a mixture of many compounds mainly of the hydrocarbon type.
6. It also contains compounds of oxygen, nitrogen and sulphur.
7. Petroleum is extracted through oil wells and refined by fractional distillation to separate other components,
8. Aviation petrol, gasoline, diesel, kerosene, naphtha, lubricating oil, tar are all obtained from petroleum.
9. They are used as fuel and for production of dyes, pesticides, perfumes and artificial fibres.

c. Natural gas:

1. Natural gas is an important fossil fuel.
2. It is lighter than air. It is found with petroleum in underground oil wells and in some places as natural gas alone.
3. The main component of natural gas is methane (CH₄), ethane (C₂H₆), propane (C₃H₈) and butane (C₄H₁₀) are present in small proportions.
4. This gas is highly flammable.
5. This fuel can be carried over long distance by means of a gas pipeline.
6. In absence of pipeline, it is transformed under high pressure into compressed natural gas (CNG) and liquefied natural gas (LNG).

Question b.
Make a list of the components we obtain from mineral oil.
Answer:

1. Mineral oil is the liquid fuel. It is also known as petroleum or crude oil. Petroleum is refined by fractional distillation to separate other components.
2. Aviation petrol, gasoline, diesel, kerosene, naphtha, lubricating oil, tar are the components we obtain from mineral oil.

Question c.
What do we get from forest?
Answer:

1. A forest is a natural habitat of plants, animals and microbes. We get wood, firewood from trees like teak, mahogany, neem, subabhul.
2. Also we get fibers, paper, rubber, gum and aromatic substances.
3. We get many medicinal plants like Adulsa, Bel, Neem, Periwinkle, Cinnamon, Cinchona which are used for treatment of various diseases like cough, cold, diarrhea, fever, cancer, diarrhoea, nausea, malaria.
4. We get fragrant essential oils from lemon grass, vanilla, kewada, khus, eucalyptus.
5. In addition to this we get fruits, bulbs and roots, honey, sealing wax, catechu, dyes from forest.

Question d.
What are the items included in ocean resources? What are their uses?
Answer:

1. Tons of minerals are found in ocean water.
2. They are tin, chromium, phosphates, copper, zinc, iron, lead, manganese, sulphur, uranium etc.
3. We also get many types of gems, conches, shells and pearls from the sea.
4. Mineral oil and natural gas is found at the bottom of sea.

Bio-resources in oceans

• Fishes – like pomfret, seer fish as also shrimps
• prawns – they are sources of proteins and vitamins, therefore, mainly used as sea food
• Dried shrimp, Bombay duck powder – used as poultry feed and is a good manure.
• Shells – used for preparation of medicines, ornaments and decorative articles.
• Fungi – used for the production of antibiotics.
• shark and cod fish – used for producing edible oil rich in Vitamins A, D and E.
• Sea cucumbers – used as medicine for treating cancer and tumours.

Mineral resources from oceans

• Thorium – used in the production of atomic energy.
• Magnesium – used in the flash bulb of a camera.
• Potassium – the main ingredient in production of soap, glass, fertilizer.
• Sodium – used in the production of cloth and paper.
• Sulphate – used in making artificial silk.

Question e.
Why should we prevent the wastage of fuels used for vehicles?
Answer:

1. Vehicles are powered by gasoline or diesel petrol.
2. Nowadays compressed natural gas (CNG) is also used.
3. Aviation petrol, gasoline, diesel, we get from petroleum after fractional distillation.
4. Petroleum is a non-renewable source of energy.
5. It is getting depleted day by day and the demand for fuel has increased greatly due to the rapidly growing population.
6. But the reserves of petroleum (fossil fuel) are limited.
7. It is becoming difficult to meet the increased demand. So we should prevent the wastage of fuel.

Question f.
Why is the diversity of plants and animals in the forests declining?
Answer:

1. The major causes of biodiversity decline are land use changes, pollution, changes in atmosphere, CO₂ concentration, changes in the nitrogen cycle, acid rain, climate alteration and introduction of exotic species.
2. All this is due to population growth.
3. This is the main cause of the loss of biodiversity. More of wood for fuel is been used, more land is required for food production, livestock grazing etc.
4. Rainforest land is converted to industrial and residential usage, so natural habitat of birds, animals is destroyed.
5. Due to population growth most of wild land is converted to crop land. So no space for animals to live, their natural habitat is destroyed.

Question g.
Write the names of five minerals and the useful substances obtained from them.
Answer:
Some important minerals and ores are:

1. Iron ore: It is used for making farming implements, rails of railway tracks etc.
2. Manganese: Compounds of manganese are used in the preparation of medicines and for giving a pink tinge to glass. Manganese is also used in electrical appliances.
3. Bauxite: It contains 55% Aluminium. Therefore, it is used mainly in aeroplanes, transport vehicles and to make electric wire.
4. Copper: It is used to make electric wires as well as in radios, telephones, vehicles, and for making kitchen utensils and statues.
5. Mica: Mica has many uses such as in ayurvedic medicines, dyes, electric machines and equipment, wireless communication equipment, etc.

Question h.
Name the two important stages in the process of obtaining metals from ores.
Answer:
The two important stages in the process of obtaining metals from ores are extraction and purification.

3. What steps are taken for protection and conservation of natural resources?

Question a
What steps are taken for protection and conservation of natural resources?
Answer:

1. Protection and conservation of natural resources is necessary to protect the natural world. (CNRM) Community Natural Resource Management has been promoted in recent years for biological conservation.
2. The World Conservation Union has been formed. It is the world’s leading authority and democratic platform in conservation and sustainability.
3. Young trees should not be cut. More and more trees need to be grown.
4. The stringent restrictions/ laws/ Regulations regarding use of forests should be strictly followed. Awareness is being created through Mass media.

4. Complete the Flow Chart:

Question a.

Answer:

5. How does the economic condition of a nation depend on its natural resources?

Question a.
How does the economic condition of a nation depend on its natural resources?
Answer:
1. Natural resources are a necessary condition for economic growth.
2. Three circles enclosed within one another shows how both economy and society are subsets of our planetary ecological system.

3. Natural resource economics deals with the supply, demand and allocation of the Earth’s natural resources.
4. Economic growth is an increase in the value of goods and services produced in an economy.
5. The natural resources of a country depend on the climatic and environmental conditions.
6. Countries having plenty of natural resources enjoy good growth than countries with small amount of natural resources.
7. A country having skilled and educated work force with rich natural resources takes the economy on the growth path, because skilled and educated people can efficiently utilize or exploit natural resources, e.g. Saudi Arabia: their economic growth is high, because they have oil wells.
8. All countries import fuel or oil from them so Saudi Arabia is economically a rich country.

6. Which medicinal plants will you grow on your school premises and near your house? Why?

Question a.
Which medicinal plants will you grow on your school premises and near your house? Why?
Answer:
1. I will grow tulsi, neem, lemon grass, bel, adulsa, periwinkle, cinnamon, ashwagandha, shatavari, amla, hirda, behda.
2. These plants are used for treatment of various diseases.

• Tulsi → for cough and cold.
• Amla, hirda, behda → Help in digestion of food or any stomach related problems.
• Adulsa → for cough and cold
• Bel → for Diarrhoea
• Neem → Fever and cold
• Periwinkle → Cancer
• Cinnamon → Diarrhoea, nausea.
• Cinchona → Malaria.
• Ashwagandha → It can reduce blood sugar levels. It can reduce stress and anxiety, may reduce symptom of depression.
• Shatavari → has been used for centuries in Ayurveda to support the reproductive system.
• Amla → Excellent source of vitamin C. Amla juice is best tonic to keep you younger for long.
• Hirda → This fruit is commonly called Haritaki. It is used for treating arthritis, dental problems like caries, bleeding gums.
• Behda →(Beleric) is a rejuvenative and laxative, proves beneficial for hair, throat and eyes.
• Tulsi → Tulsi has germicidal, fungicidal, anti-bacterial anti-biotic properties, cures fever. Treats diabetes, protects the heart. Tulsi has anti-oxidant component Eugenol which keeps one’s blood pressure under control.

Project:

Question 1.
Collect conches and shells of various shapes and colours and make a decorative article.

Question 2.
Collect information about the mines of various minerals.

Class 7 Science Chapter 16 Natural Resources Important Questions and Answers

Fill in the blanks:

Question 1.
………….. is the major raw material for biogas.
Answer:
cow dung

Question 2.
Atomic energy is obtained by using ores of ………….. .
Answer:
Uranium

Question 3.
Biogas generation is mainly based on the principle of ………….. .
Answer:
Fermentation

Question 4.
Floods can be prevented by ………….. .
Answer:
Afforestation

Question 5.
Coal, petroleum, natural gas are ………….. resources.
Answer:
non-renewable

Question 6.
The total percent of land of world under forest cover is ………….. .
Answer:
30%

Question 7.
A naturally occurring substance ………….. .
Answer:
minerals

Question 8.
Minerals that contain a high proportion of metal are called ………….. .
Answer:
ore

Question 9.
Coal, mineral oil and natural gas are ………….. .
Answer:
fossil fuel

Question 10.
Deposits of common salt are also found in the earth. This salt is called ………….. .
Answer:
rock salt

Question 11.
………….. is the liquid fuel formed by the decomposition of organic substances.
Answer:
Mineral oil

Question 12.
The underground mineral oil is extracted through ………….. .
Answer:
oil wells

Question 13.
Mineral oil is also known as ………….. or ………….. .
Answer:
petroleum, crude oil

Question 14.
………….. are the preserved remains of dead organisms in rock.
Answer:
Fossil

Question 15.
Coal can be formed from ………….. .
Answer:
Fossils

Question 16.
Impurities of sand and soil in ore are called ………….. .
Answer:
Gangue

Question 17.
Coal mainly contains ………….. .
Answer:
carbon

Question 18.
Petroleum is formed from ………….. .
Answer:
organisms in sea

Question 19.
Separation of various fractions of petroleum is called ………….. .
Answer:
Refining

Question 20.
We can obtain minerals from rocks by ………….. .
Answer:
mining

Question 21.
………….. is the most important ore of aluminium
Answer:
Bauxite

Question 22.
………….. is the coal of the highest grade.
Answer:
Anthracite

Question 23.
Metals are obtained from their ore by ………….. and ………….. .
Answer:
extraction, purification

Question 24.
………….. is the largest oil and gas research and production company in India.
Answer:
ONGC

Question 25.
Natural gas is transformed under high pressure into ………….. and ………….. .
Answer:
LNG and CNG

Question 26.
The main component of Natural gas is ………….. .
Answer:
Methane

Question 27.
………….. and ………….. are used for adding fragrance in soaps and incense sticks.
Answer:
Sandalwood and oil of Encalyptus

Question 28.
………….. is a natural herbal medicine for cough and cold.
Answer:
Adulsa

Answer the following:

Question 1.
What is meant by natural resources?
Answer:

1. We get many substances from nature.
2. They satisfy a variety of our daily needs. Soil, stones, minerals, air, water, plants and animals on the earth are all various kinds of natural resources.

Question 2.
What are alternative fuels?
Answer:
Hydrogen, biofuels, methanol or wood alcohol, ethanol or green alcohol are some of the alternative fuels.

Question 3.
What is meant by fuels?
Answer:

1. Fuel is a substance that is used in day-to-day life and burned to generate energy.
2. Fuels such as coal, wood, oil, gas provide energy when burned.
3. Fuels are found in solid, liquid or gaseous state.

Question 4.
Which natural resources do we use as fuels?
Answer:
We use coal, mineral oil and natural gas as fuels.

Question 5.
What is meant by forests?
Answer:
An extensive area of land covered by a variety of plants is called a forest. A forest is a natural habitat of plants, animals and microbes.

Question 6.
What are the uses of forests?
OR
Write short note on forest and its uses.
Answer:

1. A forest is a natural habitat of plants, animals and microbes.
2. Forest help improve and maintain the quality of environment.
3. Forest helps in prevention of soil-erosion, help to control floods, protects wild life, maintains the balance of atmospheric gases.
4. We get many medicinal plants from forest which help in treatment of various diseases.
5. Examples Adulsa, Bel, Neem, periwinkle, amla tulsi, cinnamon.
6. We also get wood, firewood from trees like teak, mahogani, neem, sababhul. Wood is useful for making furniture, farming implements, in construction work.
7. Forest wealth includes fibres, paper, rubber, gum and aromatic substances.
8. We get fragrant essential oils from lemon grass, vanilla, kewada and eucalyptus.
9. They are used for making soaps, cosmetics and incense sticks. We get various fruits, bulbs, roots, honey, sealing wax, catechu dyes etc. from forest.

Question 7.
Are minerals to be found in seas and on the seabed as they are found inside the earth?
Answer:
Yes, there are very large reserves of tin chromium, phosphates, copper, zinc, iron, lead, manganese, sulphur, uranium etc. in the ocean and seabed.

Question 8.
How is mineral oil formed?
Answer:

1. Mineral oil is the liquid fuel formed by the decomposition of organic substances buried underground.
2. Millions of years ago, bodies of dead sea organisms sank to the bottom of the sea.
3. Layers of soil and sand collected on them.
4. Due to high pressure and temperature the remains of the dead organisms were transformed into mineral oil.
5. The underground mineral oil is extracted through oil wells.

Use your brain power!

Question 1.
Why are all minerals not ores?
Answer:

1. Minerals that contain a high proportion of metal are called ores.
2. Majority of the metals occur in the form of compounds called ores.
3. But all minerals are not ores.
4. Few metals like gold, silver, copper, platinum and bismuth occur in free state in nature. So all minerals are not ores.

Question 2.
What is meant by metal mineral and non¬metal mineral?
Answer:

1. Metal-minerals contain metallic elements in their chemical formula. So they are called metal-minerals, for example, iron, copper, gold, silver etc.
2. They contain metal in raw form.
3. Non-metallic minerals do not contain metal elements in their inorganic chemical formula Example, Clay, Diamond, Dolomite, Gypsum, Mica, Quartz.

Question 3.
Why is mineral oil called ‘liquid gold’?
Answer:
Because of its high price and value and its economic need, the mineral oil is called liquid gold. It’s reserve is less and demand is more.

Question 4.
Why is coal called black gold?
Answer:

1. Coal is a storehouse of carbon. Coal is used as a fuel, in thermal power plants as well as to run boilers and railway engines.
2. It is used as a fuel for cooking and for baking bricks in kilns on a large scale.
3. The gaseous fuels, producer gas and water gas are obtained from coal.
4. Coal as an energy resource, contributes greatly to industrial development.
5. As coal is black in colour and worth a lot of money just like gold, it is called black gold.

Question 5.
What would happen if underground mineral resources are exhausted?
Answer:

1. Coal, petroleum and other mineral are all non-renewable sources of energy.
2. The reserve is less and demand is more. They would get exhausted one day.
3. If such a situation occurs, we will not get electricity.
4. All our household and industries depend on electricity.
5. Transportation and household items, and food items would become very costly.
6. The survival of human life will be ver\ difficult.

Question 6.
Why is natural gas an eco-friendly fuel?
Answer:

1. Natural gas is an important source of energy which is eco-friendly because of its low carbon dioxide emission.
2. When burned it produces 45% less CO₂ than coal, 30% less than oil, and about 15% less than wood.
3. It does not produce carbon monoxide, sulphur dioxide or airborne particles, all of which are harmful to human and animal health.
4. It is referred as the clean energy source and is fuel for the present century as it does not ‘ pollute the atmosphere or contribute to global warming.

Question 7.
What useful things will we have to do without if rubber is no longer available?
Answer:

1. Rubber has played a largely hidden role in global environment history for more than 150 years.
2. In industries, rubber is needed to connect and protect all moving parts of machines.
3. Native people used rubber for rubber boots.
4. Household uses rubber in everything viz dish washing gloves, toys, jar seals, tyres in vehicles.
5. Welcome mat at the door, Boots, raincoats, mattress cushions, earplugs, hot water bottles, surgical tubing and gloves, in labs, birth control device.
6. In schools rubber bands, erasers, mouse pads, key board, rolling chair wheels. Head phone pads, rubber stamps are useful items used in schools and offices.

Question 8.
What are the adverse effects of clearing of forest or cutting down trees?
Answer:

1. Clearing of forest is also called Deforestation.
2. Removal or cutting down of trees has resulted in damage to habitat, biodiversity loss and aridity.
3. If has adverse impacts on concentration of atmospheric carbon dioxide. (Trees use up carbon dioxide from the atmosphere for the process of photosynthesis.)
4. Deforestation is a main contributor to global warming. Major cause of enhanced greenhouse effect. Deforestation cause carbon dioxide to linger in the atmosphere.
5. Deforestation reduced the content of water in the soil and ground water and atmospheric moisture, because trees extract ground water through the roots and release it into the atmosphere.
6. When a part of forest is removed the trees no longer transpire this water, resulting in much drier climate.
7. Due to deforestation soil erosion and flooding, landslide problems occur.
8. Deforestation results in decline in biodiversity, on a natural global scale is known to cause the extinction of many species.
9. Forest is habitat for wild life, and many medicinal plants. If forests are removed it will affect wild life and also we will not get medicinal plants.

Find out:

Question 1.
How did the various ages of the prehistoric period get their names on the basis of the uses of metals.
Answer:
1. The three-age system in history archaeology, and physical anthropology is a methodological concept adopted during the 19th century by which artifacts and events of late prehistory and early history could be ordered into a recognizable chronology.

2. Initially developed by C. J. Thomson, director of the Royal Museum of Nordic Antiquities, Copenhagen – as a means to classify the museum’s collection according to whether the artifacts were made of stone, bronze or iron.

3. Depending-upon the use of stone, bronze, iron, that period was known as stone age, bronze age, and iron age, respectively.

Answer the following:

Question 1.
Write down the difference between Metal minerals and Non-metallic minerals.
Answer:

Question 2.
Write down the different types of coal.
Answer:
Peat, lignite (brown coal), bituminous coal and anthracite are various types of coal.
Anthracite is the coal of the highest grade.

Question 3.
Write down the characteristics of Compressed Natural Gas.
Answer:
Characteristics of CNG:

1. Catches fire easily.
2. No solid waste remains after combustion.
3. Carbon dioxide and water are formed in small quantities.
4. Other pollutants are not produced.
5. Can be transported easily.
6. Combustion can be controlled easily.

Observe the pictures and answer the question.

Question a.
What is the process shown in the given picture?
Answer:
The process shown is formation of mineral oil and natural gas.

Question b.
Explain the process.
Answer:

1. Mineral oil is the liquid fuel formed by the decomposition of organic substances buried underground.
2. Millions of years ago, bodies of dead sea organisms sank to the bottom of the sea.
3. Layers of soil and sand collected on them.
4. Due to high pressure and temperature the remains of the dead organisms were transformed into mineral oil.
5. The underground mineral oil is extracted through oil wells.

Question c.
What are the gaseous substances formed in the above process?
Answer:
Natural gas is also formed along with mineral oil. It contains methane, ethane, propane and butane gases.

Question d.
When the products of the process is refined, what other components are produced?
Answer:
When mineral oil is refined by fractional distillation products produced are petrol, diesel, kerosene, naphtha lubricating oil, tar, etc.

Maharashtra State Board Class 7 Science Solutions Chapter 20 In the World of Stars

Class 7 Science Chapter 20 In the World of Stars Textbook Questions and Answers

1. Write the proper words in the blanks:
(meridian, horizon, twelve, nine, apparent, celestial, ecliptic)

Question a.
When seen from a great distance, the sky seems to be touching the ground along a circle. This circle is called the …………… .
Answer:
horizon

Question b.
The ………….. is used while defining the zodiac sign.
Answer:
meridian

Question c.
Classified according to seasons, one season will have ………… nakshatras.
Answer:
nine

Question d.
The rising of the sun in the east and its setting in the west is the ………. motion of the sun.
Answer:
apparent

2. A star rises at 8 pm. tonight. At what time will it rise after a month? Why?

Question a.
A star rises at 8 pm. tonight. At what time will it rise after a month? Why?
Answer:

1. Str s rise and set 4 minutes earlier every day. If star rises at 8 pm tonight, it will rise at 7:56 pm tomorrow.
2. It will rise at 5:24 pm after a month.
3. The sun and the moon are seen to move from the west to the east against the background of stars.
4. The sun moves through one degree every day and the moon through 12 to 13 degrees.
5. This happens due to the motion of the earth around the sun and the moon around the earth which affects the duration of the stars and shortens its time period.

3. What is meant by “The sun enters a nakshatra?” It is said that in the rainy season the sun enters the mrug nakshatra. What does it mean?

Question a.
What is meant by “The sun enters a nakshatra?” It is said that in the rainy season the sun enters the mrug nakshatra. What does it mean?
Answer:

1. When we look at the sun we see not only the sun but also constellation behind the sun.
2. The constellation cannot be seen in bright sunlight but it is indeed present behind the sun.
3. As the earth changes its position, a different constellation or zodiac sign or raashi appears behind the sun.
4. This is what we express when we say that the sun enters a particular zodiac sign or raashi.
5. In rainy season due to the perceived motion of the sun, it enters mrug nakshatra and that is how it is expressed.

4. Answer the following questions. 

Question a.
What is a constellation?
Answer:
A group of stars occupying a small portion of the celestial sphere is called a constellation.

Question b.
What points should be considered before a skywatch?
Answer:

1. The place for sky watching should be away from the city and as far as possible it should be new moon night.
2. Binoculars or telescopes should be used for skywatch.
3. Identifying the pole star in the north makes the skywatch easier. Hence the pole star should be used as a reference point for skywatch.
4. As the stars in the west set early, sky watching should begin with stars in the west.
5. (a) On a sky map, the north and south are towards the bottom and top of the map respectively, (b) This is because the sky map is to be held overhead in such a way that the direction we face is at the bottom side.

Question c.
It is wrong to say that the planets, stars and nakshatras affect human life. Why?
Answer:

1. Science has proved that the constituents of the solar system e.g. planets, satellites and comets as also distant stars and constellations do not have any influence on human life.
2. Man has stepped on the moon and will conquer Mars in the 21st century.
3. Hence, in this age of science, holding on to beliefs which have been proved wrong by numerous scientific tests, is an unnecessary waste of time and energy.
4. It is important to consider all these issues with a scientific frame of mind.

5. Write a paragraph on the birth and life cycle of stars using following figure.

Question a.
Write a paragraph on the birth and life cycle of stars using following figure.
Answer:
Stars are born out of nebulae. Nebulae are clouds made up mainly of hydrogen gas and dust particles which are attracted towards one another by the force of gravity, (i) As a result of pressure, the internal temperature increases and the cloud becomes dense and spherical in shape, (ii) From the diagram, life cycle of two stars can be explained.

(a) Ordinary star: (i) The ordinary star forms a Red giant star at the later stage of its evolution when it runs out of hydrogen gas at its core. (ii) At the end stage of its life it forms a white dwarf. Stars like the sun become white dwarf when its nuclear fuel is totally exhausted. (iii) It is 1% in diameter of its original size.

(b) Massive Star: (i) Massive star forms Red super giant star at the end of its life cycle, (ii) They are also called super red giants with a relatively cool outer surface, (iii) Supernova is the explosive death of the star of the end of its life with the brightness of 100 million stars in a short amount of time, (iv) A neutron star is the dense core of the supernova. (v) It is the smallest and the densest star known to exist with a 10 km radius, (vi) Neutron stars sometimes end as a black hole, (vii) Black holes are not seen from telescopes and are identified by their intense gravitational pull where even light cannot escape.

Project:

Question a.
Visit a planetarium, collect information and present it in your school on Science day.

Class 7 Science Chapter 20 In the World of Stars Important Questions and Answers

Fill in the blanks:

Question 1.
The different group of stars is known as ………….. .
Answer:
constellation

Question 2.
The pole star is ………….. .
Answer:
North star

Question 3.
The moon moves around the earth in about ………….. days.
Answer:
27 days

Question 4.
The celestial objects are ………….. .
Answer:
The stars

Question 5.
The star that lies close to the aris of rotation of the earth ………….. .
Answer:
Pole star

Question 6.
The definite elliptical path in which a planet revolves around the sun is called ………….. .
Answer:
Orbit

Question 7.
Our earth as well as the sun belongs to the galaxy which has a spiral shape called ………….. .
Answer:
milky way

Question 8.
………….. is made up of five bright stars which are distributed along the figure of the letter M.
Answer:
Sharmishtha

Question 9.
The pole star has ……………. on one-side and ……………… on the other.
Answer:
Saptarashi, Sharmishtha

Question 10.
The continuous empty space between the planets and stars in the sky is called ………….. .
Answer:
space

Name the following:

Question 1.
The brightest star in the nakshatra.
Answer:
Yogatara

Question 2.
The stars forming a group that has a recognizable shape.
Answer:
Constellation

Question 3.
Millions of stars and planets present in the sky forming a group.
Answer:
Milky way

Question 4.
The clouds from which stars are bom.
Answer:
Nebulae

Question 5.
Saptarshi constellation in English.
Answer:
Great Bear

Question 6.
The festival celebrated when sun enters Makar raashi.
Answer:
Makara Sankranti

Question 7.
The brightest star in the Orion constellation.
Answer:
Sirius

State whether the following statements are True or False. Correct the false statements:

Question 1.
The hydrogen gas and dust particles in a nebulae are attracted towards each other by gravity.
Answer:
True

Question 2.
While standing on the ground, the celestial sphere exactly below our feet is called the Zenith.
Answer:
False. The point on the celestial sphere exactly above our head is called the Zenith

Question 3.
The circle describing the apparent motion of the earth around the sun is called the ecliptic.
Answer:
False. Ecliptic is the apparent motion of sun around the earth

Question 4.
Vrushchik or Scorpio is a constellation with 10 to 12 stars.
Answer:
True

Question 5.
Makar raashi is also known as Capricorn zodiac sign.
Answer:
True

Match the following:

Question a.

Answer:

Answer in one line:

Question 1.
In which direction stars move in the sky except polar star?
Answer:
When seen from earth, stars appear to move from east to west.

Question 2.
What activity does IUCAA carry out?
Answer:
IUCAA which is present in PUNE carries out fundamental research in astronomy.

Question 3.
Define constellation.
Answer: A group of stars occupying a small portion of the celestial sphere is called constellation.

Question 4.
What is Nakshatra?
Answer:
The moon completes one revolution around the earth in approximately 27 days. The portion celestial sphere traversed by the moon in one day is called a nakshatra.

Question 5.
What is yogatara?
Answer:
A nakshatra is known from the brightest star that it contains. The brightest star is called the yogatara.

Define the following:

Question 1.
Horizon
Answer:
Far away the sky seems to be touching the ground. The line at which they meet is caled horizon.

Question 2.
Zenith
Answer:
While standing on the ground the point on the celestial sphere exactly above our head is called the Zenith.

Question 3.
Nadir
Answer:
While standing on the ground the point on the celestial sphere exactly below our feet is called the nadir.

Question 4.
Meridian
Answer:
The great circle which passes through both the celestial poles and the observer’s zenith and nadir is called a meridian.

Question 5.
Celestial equator
Answer:
If we uniformly expand earth’s equator in all directions indefinitely, it will penetrate the celestial sphere along a circle. This circle is known as the celestial equator.

Question 6.
Ecliptic
Answer:
The earth moves around the sun, but seen from the earth, the sun appears to move along a circle on the celestial sphere. This circle describing the apparent motion of the sun around the ‘ earth is called the ecliptic.

Question 7.
Zodiac sign
Answer:
The ecliptic has been imagined to divided into 12 equal parts. Each part subtends 30 degrees at the centre of the celestial sphere. Each of these part is called a raashi or zodiac sign.

Question 8.
Mrug Nakshatra or Orion
Answer:
It has 7 – 8 starts of which four are at the comers of quadrangle. The line passing through the three middle stars of the constellation when extended meets a very bright star. This is Vyadh or Sirius.

Find out.

Answer the following questions

Question 1.
Using a Marathi calendar collect information about 27 nakshatras, and divide them into the following 3 categories.
(i) Monsoon Nakshatra (ii) Winter Nakshatra (iii) Summer Nakshatra
Answer:
27 nakshtras: Ashwini, Bharani, Krittika, Rohini, Mrigashirasha, Ardra, Punarvasu, Pushya, Ashlesha, Magha, PurvaPhalguni, Uttara Phalguni, Hasta, Chitra, Swati, Vishakha, Anuradha, Jyeshtha, Mula, Purva Ashadha, Uttara Ashadha, Abhijit, Shravana, Dhanishtha, Shatabhishta, Purva Bhadrapada, Uttara Bhadrapada, Revati

Question 2.
Write the difference between constellations Saptarshi and Mrug nakshatra
Answer:

Question 3.
Draw sketches to show the relative position of prominent stars in Ursa major and Orion.
Answer:
a. Ursa major (Saptarshi) appears like a big dipper, (or kite shape). There are 3 bright stars in the handle and 4 stars in the bowl of the dipper. (It can be seen during April in summer in northern skies).

(b) Orion appears like a hunter. Three bright stars appear in the belt, 5 bright stars are arranged in the form of a quadrilateral. (It is visible during winter in the northern skies)

Question 4.
Why is the pole star important for sky watch?
Answer:

1. Identifying the Pole Star in the north makes the sky watch easier. Hence the pole star should be used as a reference point for skywatch.
2. If we extend one side of the quadrangle of Saptarshi, it reaches the Pole Star.
   The pole star has Saptarshi on one side and Sharmishtha on the other.

Question 5.
What is the relation between the pole star and the constellations Saptarshi and Sharmishtha?
Answer:

1. Saptarshi is in the shape of a quandrangle with a tail made up 3 stars resembling a kite. If we extend one side of the quadrangle it reaches the Pole Star.
2. The constellations of Saptarshi and Sharmishtha are useful in locating the Pole Star.
3. The perpendicular bisector of the line joining the third and fourth stars in Sharmishtha goes towards the Pole star.
4. The Pole Star has Saptarshi on one side and Sharmishtha on the other.

Use your brain power!

Answer the following questions.

Question 1.
One Zodiac Sign = ………….. nakshatras
Answer:
27 nakshatras. Each nakshatra is divided in padas or charan. Every nakshatra has 4 padas. These 27 nakshatra complete the entire circle of 360° of zodiac.
The zodiac comprises of 360°.

Question 2.
Is sun the only star present in our Milky Way galaxy?
Answer:
No. Sun is not the only star present in the Milky Way. There are lakhs of stars in the Milky Way, some of them being many times bigger than our sun. Some of them have their own planetary systems with a great diversity in colour, brightness, as well as size.

Maharashtra State Board Class 6 Science Solutions Chapter 5 Substances in the Surroundings – Their States and Properties

Class 6 Science Chapter 5 Substances in the Surroundings – Their States and Properties Textbook Questions and Answers

1. In the paragraph below write ‘solid’, ‘liquid’ or ‘gas’ in each of the blank (brackets) depending on the substance referred to just before.

Question a.
On a bright sunny day, Riya and Gargi are playing with a ball (…..) in the park. Gargi feels thirsty. So, Riya brings tender coconut water (…..) for her. At the same time, a strong breeze (…..) starts blowing and it also begins to rain (…..). They run back into the house (…..), change their clothes (…..) and then their mother gives them a cup (…..) of hot milk (…..) to drink.
Answer:
solid, liquid, gas, liquid, solid, solid, solid, liquid.

2. Discuss.

Question a.
Riya pours some water from her bottle into another bottle. Does it change the shape of the water?
Answer:
Yes, the shape of water changes as water is in liquid state. Liquids do not have a shape of its own. They take the shape of the container.

Question b.
Halima picks up a small stone from the ground and puts it in the water in a dish. Does the shape of the stone change?
Answer:
No, the shape of the stone does not change. Stone is a solid, hence retains its shape.

3. Write the properties of these substances.
(water, glass, chalk, iron ball, sugar, salt, flour, coal, soil, pen, ink, soap)

Question a.
Write the properties of these substances.
(water, glass, chalk, iron ball, sugar, salt, flour, coal, soil, pen, ink, soap)
Answer:
Properties of substances:

4. What is sublimation? Write the names of everyday substances that sublimate.

Question a.
What is sublimation? Write the names of everyday substances that sublimate.
Answer:

1. The change of a solid substance directly into a gas or vapour without first changing into liquid is called sublimation.
2. Substances that sublimate: Camphor, napthalene balls, ammonium chloride, iodine.

5. What is made from? Why? 
a. A sickle to cut sugarcane.
b. The sheets used for roofing.
c. A screwdriver
d. A pair of tongs.
e. Electric cables.
f. Ornaments.
g. Pots and pans.

Question a.
A sickle to cut sugarcane.
Answer:
A sickle is made of iron. An iron sickle is hard and malleable. When sharpened it will be able to cut the hard sugarcane.

Question b.
The sheets used for roofing:
Answer:

1. The sheets used for roofing are made of plastic, aluminium.
2. Plastic is hard, hence, protects against weather conditions.
3. Plastic is transparent, hence, sunlight can pass through it.
4. Aluminium is hard, light weight and durable, hence, protects against all weather conditions.
5. Malleable hence formed into thin sheets.

Question c.
A screwdriver:
Answer:

1. A screwdriver is made up of iron, steel, aluminium.
2. A screwdriver possesses property of hardness hence, it easily pierces a screw in piece of wood, wall, metals etc.

Question d.
A pair of tongs:
Answer:

1. A pair of tongs are made up of iron, steel aluminium etc. Tongs are used to lift hot, boiling utensils or vessels.
2. Tongs are hard, ductile and malleable.
3. Hence, have strong grip to hold utensils.
4. Rubbers fitted on the ends will protect from thermal conduction, from bums.

Question e.
Electric cables:
Answer:

1. Electric cables are metal wires (thin) wound in plastic.
2. Metal wires possess the property of hardness, ductility, electrical conductivity.
3. Plastic /rubber covering possesses the property of hardness, elasticity and are bad conductors of heat and electricity.

Question f.
Ornaments:
Answer:

1. They are made up of metals like gold and silver.
2. They possess the property of hardness, ductility, malleability, lustre.

Question g.
Pots and pans: Answer:

1. They are used to cook food, hence metals like aluminium, steel are used.
2. They possess the property of hardness, ductility, malleability, thermal conductivity, electrical conductivity, (microwave ovens)

6. What will happen if ….? And why?

Question a.
Nails are made of plastic
Answer:
If nails are made of plastic, they will not be able to pierce through other substances on being pushed or forced by a hammer. Plastic lacks the property of hardness.

Question b.
A bell is made of wood.
Answer:

1. If a bell is made of wood it will never make a ringing sound. A wooden bell does not have the property of being sonorous.
2. Sonority is the property of metals to produce a ringing sound.

Question c.
Rubber is not fitted on a pair of tongs.
Answer:

1. Rubber is a bad conductor of heat and electricity. It will not allow heat to pass to the hands/handle of the tongs, thus protecting us.
2. Pair of tongs are made up of metals which conduct heat and electricity. They have file property of thermal conduction and electrical conduction.
3. If rubber is not fitted on a pair of tongs, we will not be able to lift hot objects with it.

Question d.
A knife is made of wood.
Answer:
Wood does not have the property of malleability. Therefore, the edge of wooden knife will be blunt. Hence, we will not be able to cut anything with it.

Question e.
An axe is made of rubber.
Answer:

1. If an axe is made of rubber, it will not be used to cut wood or tree.
2. Rubber does not have the property of hardness that is required to push through to cut it.

7. Who am I?

Question a.
I’m found in a thermometer, I measure your temperature.
Answer:
Mercury

Question b.
I make things hot or cold.
Answer:
Heat

Question c.
I have no shape whatsoever!
Answer:
Liquid, gases

Question d.
I dissolve in water, but not in kerosene.
Answer:
Salt

8. Why does this happen? 

Question a.
Coconut oil thickens in winter.
Answer:
Coconut oil is in liquid state. In winter the surrounding temperature / atmospheric temperature starts decreasing. Coconut oil starts cooling or losing heat, it changes to solid state.
Thus coconut oil thickens in winter.

Question b.
Kerosene left open in a dish disappears.
Answer:
When kerosene is left open in a dish, it is exposed to surrounding temperature. As the temperature is more, kerosene starts continuously evaporating and finally disappears.

Question c.
The fragrance of incense sticks lighted in one corner of a room spreads to the other corner.
Answer:
The fragrance of incense sticks is given out in the form of scented vapours. As vapours are in gaseous state, the gas molecules spread out in the room. The molecules of gas move very fast and there are no forces to stop them from going apart. Therefore the fragrance of incense sticks lighted in one corner of room spreads to the other corner.

Question d.
What you see in the picture.

Answer:
The mass of plastic ball is less than an apple. This difference is because of their densities. Since an apple has greater density, it will sink to the bottom on other hand the plastic ball has lesser density, it will float over water surface.

Activity: 

Question 1.
Find out how the big statues of wax are made.

Question 2.
Visit a jeweller’s shop and find out how ornaments are made.

Class 6 Science Chapter 5 Substances in the Surroundings – Their States and Properties Important Questions and Answers

Fill in the blanks:

Question 1.
The state of a substance changes if it is …………… or …………… .
Answer:
heated, cooled

Question 2.
Every substance in our surroundings is found in either the ……………, …………… or gaseous state.
Answer:
solid, liquid

Question 3.
On …………… heat, the substance changes from solid to liquid and liquid to gas.
Answer:
gaining

Question 4.
When the substance cools, or …………… heat, it changes from gaseous to liquid and liquid to solid state.
Answer:
loses

Question 5.
A …………… amount of heat must be gained or lost before the state of a substance can change.
Answer:
specific

Question 6.
When a substance gets heat, it becomes …………… and then …………… .
Answer:
warm, hot

Question 7.
If the substance is very hot, we could get …………… .
Answer:
scalded

Question 8.
A thermometer is used to measure …………… .
Answer:
temperature

Question 9.
…………… is the unit of measuring temperature.
Answer:
Degree Celsius (°C)

Question 10.
Nowadays, …………… thermometers are frequently used.
Answer:
digital

Question 11.
Solids have a shape of its …………… .
Answer:
own

Question 12.
Solids have a …………… volume.
Answer:
definite

Question 13.
Liquids take the shape of the …………… .
Answer:
container

Question 14.
Liquids have a …………… volume.
Answer:
specific

Question 15.
Air occupies all the available …………… .
Answer:
space

Question 16.
Evaporation occurs from the …………… of the water.
Answer:
surface

Question 17.
At sea-level, pure water boils at …………… .
Answer:
100°C

Question 18.
Condensation of steam takes place at …………… .
Answer:
100°C

Question 19.
The temperature of a substance can fall below …………… .
Answer:
0°C

Question 20.
Ice melts at …………… .
Answer:
0°C

Question 21.
Each substance has a specific boiling point which is also its …………… point.
Answer:
condensation

Question 22.
Each substance has a specific melting point which is the same as its …………… point.
Answer:
freezing

Question 23.
Candles are made by melting …………… wax.
Answer:
paraffin

Question 24.
Solid carbon-dioxide is …………… .
Answer:
dry ice

Question 25.
Liquid …………… is used in animal husbandry.
Answer:
nitrogen

Question 26.
Sand is melted to make …………… .
Answer:
glass

Question 27.
Iron is melted to make …………… .
Answer:
tools

Question 28.
Substances can be identified by studying their …………… .
Answer:
properties

Question 29.
Substances that break into small particles are said to be …………… .
Answer:
brittle

Question 30.
The …………… of any liquid is determined by how easily it flows.
Answer:
fluidity

Question 31.
Between substances of the same volume, the ones with greater density are …………… than those of lesser density.
Answer:
heavier

Question 32.
The property of a substance of getting …………… is called its solubility.
Answer:
dissolved

Question 33.
Minerals from the earth’s crust are …………… to obtain metals.
Answer:
processed

Question 34.
Metals can be converted into …………… by hammering.
Answer:
sheets

Question 35.
Metals can be stretched and drawn into …………… .
Answer:
wires

Question 36.
All metals are …………… of electricity to a greater or lesser extent.
Answer:
conductors

Question 37.
Every metal has a …………… colour by which it can be identified.
Answer:
specific

Question 38.
Metals produce …………… sound.
Answer:
ringing

Question 39.
Metals form a …………… group of substances.
Answer:
separate

Question 40.
Heat is the cause of the change of the state of …………… .
Answer:
substances

Match the columns:

Question 1.

Answer:

Answer in one sentence:

Question 1.
What is change of state of substances?
Answer:
When a substance changes from one state to another, the process is called change of state of the substance.

Question 2.
When does state of substance change?
Answer:
State of substance changes when it is heated or cooled.

Question 3.
In which state do substances exist in our surroundings?
Answer:
The substances exist in solid, liquid and gaseous form in our surroundings.

Question 4.
What happens when a substance gains heat?
Answer:
When a substance gains heat, it changes its state i.e. from solid to liquid and liquid to gas.

Question 5.
What happens when a substance loses heat?
Answer:
When a substance loses heat, it changes its state from gaseous to liquid and liquid to solid state.

Question 6.
How do we tell how hot or cold a substance is?
Answer:
The temperature on the thermometer will tell us how hot or cold a substance is.

Question 7.
What is the unit of measuring temperature.
Answer:
Degrees Celsius (°C) is the unit of measuring temperature.

Question 8.
What is the boiling point of water?
Answer:
The boiling point of water is 100° C.

Question 9.
What is condensation?
Answer:
When vapour cools, it is converted into liquid again. This process is condensation.

Question 10.
At what temperature condensation of steam takes place?
Answer:
Condensation of steam takes place at 100° C.

Question 11.
What is the freezing point of water?
Answer:
0° C is the freezing point of water.

Question 12.
What is the temperature of air in the freezer of a refrigerator?
Answer:
-18° C is the temperature of air in the freezer of a refrigerator.

Question 13.
At what temperature ice melts?
Answer:
Ice melts at 0° C.

Question 14.
How are candles made?
Answer:
Candles are made by melting paraffin wax.

Question 15.
What is the use of solid carbon-dioxide?
Answer:
Solid carbon-dioxide (dry ice) is used to make ice cream and to keep it frozen.

Question 16.
What is the use of liquid nitrogen?
Answer:
Liquid nitrogen is used in animal husbandry.

Question 17.
What is sublimation?
Answer:
The change of a solid substance directly into gas or vapour without changing into a liquid is called sublimation.

Question 18.
Define brittleness / What is brittleness?
Answer:
Some substances break into small pieces or particles. Such substances are said to be brittle. This property of substances is called brittleness.

Question 19.
Define hardness / What is hardness?
Answer:
The hardness of a substance is determined by how much resistance it offers to the substances being pushed through it.

Question 20.
Define elasticity / What is elasticity?
Answer:
Some substances change their shape when a force is applied on them but return to their original shape and size when the force is removed. This property is called elasticity.

Question 21.
Define fluidity / What is fluidity?
Answer:
Liquids flow downward on a sloping surface. This property is called fluidity.

Question 22.
How is fluidity of any liquid determined?
Answer:
Fluidity of any liquid is determined by how easily it flows.

Question 23.
Define density / What is density?
Answer:
The mass of different substances having the same volume can be different. This difference is because of the difference in their densities. Between substances of the same volume, the ones with greater density are heavier than those of lesser density.

Question 24.
Define solubility / What is solubility?
Answer:
The property of a substance of getting dissolved is called its solubility.

Question 25.
Define transparency / What is transparency?
Answer:
When we can look through a substance and see things on the other side, then that substance is said to be transparent. This property of the substances is called transparency.

Question 26.
List some transparent substances.
Answer:
Glass, air, clean water and some types of plastic are transparent substances.

Question 27.
What are metals?
Answer:
Metals are substances like copper, gold, iron, aluminium. They are found in the form of minerals deep inside the earth. Minerals from the earth’s crust are processed to obtain metals.

Question 28.
Define malleability. / What is malleability?
Answer:
Metals can be converted into sheets by hammering. This property of metals is called malleability.

Question 29.
Define ductility. / What is ductility?
Answer:
Metals can be stretched and drawn into thin wires. This property of metals is called ductility

Question 30.
Name some ductile metals.
Answer:
Metals like silver, gold, platinum can be drawn into fine wires.

Question 31.
Define electrical conductivity. / What is electrical conduction?
Answer:
Electricity flows through metals. All metals are conductors of electricity to a greater or lesser extent.

Question 32.
Define thermal conductivity. / What is thermal conductivity?
Answer:
Metals allow heat to flow through them. This property is called thermal conductivity

Question 33.
What is lustre?
Answer:
The typical shine or characteristic colour by which metal can be identified is called lustre.

Question 34.
What is sonority of metals? / Define sonority.
Answer;
Metals produce a ringing sound. This property is called the sonority of metals.

Give scientific reasons for following:

Question 1.
Metals are used to make musical instruments.
Answer:
Metals possess the property of being sonorous, i.e. produce a ringing sound. Hence, they are used to make musical instruments.

Question 2.
Ornaments are made up of metals.
Answer:
Metals have the property of being malleable, ductile, lustrous. Hence, ornaments are made up of metals.

Question 3.
Why should we not put our hand or finger in the water to judge the hotness of water?
Answer:
We should never put our hand or finger in the water to judge how hot it is because that is not an accurate measure. Besides if the substance is very hot, we could get scalded.

Can you tell?

Question 1.
Why are electric boards fitted on the wall made of plastic or wood?
Answer:
Plastic or wood are bad conductors of heat and electricity. Electric boards are made up of plastic or wood. So that while touching we will not get electric shock.

Question 2.
The handle of cooker is made of plastic. Why?
Answer:
Cooker is made of metal. When food is cooked in it, it gets heated and the whole of its body becomes hot due to thermal conductivity. Hence with the plastic handle we can easily lift the hot cooker as plastic is a bad conductor of heat.

Question 3.
Use your brain power!
On opening a box of camphor, its smell spreads all around. Why does this happen?
Answer:

1. Camphor is a sublimate substance.
2. When a box of camphor is opened it changes its state from solid to gas or vapour state.
3. This change takes due to the process of sublimation where camphor absorbs heat from surrounding to change from solid to gaseous state.
4. Camphor particles in gaseous state start spreading all around.
5. Hence on opening a box of camphor its smell spreads all around.

Question 4.
Identify the objects shown in fig. 5.14. From which substances are they made? What are these substances called as a group?
Answer:
In fig 5.14, the metallic bars are shown, these bars are made up of shiny solid. These substances are called metals.

Question 5.
Name the solid, liquid and gaseous states of water.
Answer:

• Solid- Ice
• Liquid – water
• Gas – water vapour.

Question 6.
Read this list of substances:
spirit, camphor, petrol, ghee, coconut oil, naphthalene balls, ammonium chloride (navsagar).

Question a.
Which one freezes in winter?
Answer:
Coconut oil, ghee.

Question b.
Which liquids have you seen change into a vapour?
Answer:
Spirit, petrol.

Question c.
Which solid directly changes into gaseous state?
Answer:
Camphor, naphthalene balls, ammonium chloride.

Question 7.
The chart given below shows the boiling point and freezing point of some substances. State whether these substances are solid, liquid or gaseous at room temperature.

Answer:
Candle, plastic and iron are in solid state at room temperature.

Distinguish between solids, liquids and gases.
Answer:

Distinguish between Boiling and Melting.
Answer:

Answer the following briefly:

Question 1.
List properties of solids
Answer:

1. Solids have its own shape i.e. Retains shape, no matter how it is kept.
2. Solids have definite volume.
3. e.g. Sand when poured on a flat surface form a heap.

Question 2.
List properties of liquids.
Answer:

1. Liquid does not have a shape of its own. Takes the shape of the container.
2. A liquid has a specific volume i.e. occupies definite portion of a container.
3. Liquids: e.g. water, milk, kerosene.

Question 3.
List properties of gases.
Answer:

1. Gases does not have a shape of its own.
2. Occupies all the available space.
3. Does not have a definite volume.
4. e.g. Air.

Question 4.
Explain with example how liquids take the shape of the surface.
Answer:
Liquids have a specific volume. They occupy definite portion of a container. Liquids spreads on a flat surface on pouring. Liquids flow downwards along a slope.

Question 5.
Explain Ebullition.
Answer:

1. As the water gets heated, its temperature increases and it evaporates at a faster and faster rate.
2. When water kept on a stove attains a particular temperature or level of heat, then evaporation takes place in all parts of the body of water.
3. Then we see water bubbles rising at a faster and faster rate to the surface and steam mixing in the air.
4. This is called boiling of water or Ebullition.

Question 6.
Explain: Boiling point and condensation point of water are one and the same.
Answer:
Water boils at 100°C. i.e. boiling point of water is 100°C. Condensation of steam also takes place at 100° C. Thus boiling point and condensation point of water are one and the same.

Question 7.
Explain freezing point of water.
Answer:

1. Water kept in a fridge or on ice becomes cooler and cooler i.e. its temperature falls.
2. At a certain temperature water does not cool further but starts freezing and forms ice.
3. The temperature at which this happens is called the freezing point of water. (0° C)

Question 8.
Explain: Freezing point and melting point of water are same.
Answer:

1. The temperature at which water does not get any cooler but starts freezing and forming ice is 0° C.
2. When ice gets heat, it starts melting or changes into liquid state at 0° C.
3. Thus, freezing point and melting point of water are one and the same.

Question 9.
List various uses of changes in physical state.
Answer:

1. Candles are made by melting paraffin wax.
2. Solid carbon-dioxide (dry ice) is used to make ice-cream and to keep it frozen.
3. Liquid nitrogen is used in animal husbandry.
4. Sand (silica) is melted to make glass.
5. Metals like gold and silver are melted to make ornaments.
6. Iron is melted to make tools.

Question 10.
List the properties of substances:
Answer:
The properties of substances are

1. Brittleness
2. Hardness
3. Elasticity
4. Fluidity
5. Density
6. Solubility
7. Transparency

Question 11.
List properties of metals:
Answer:
The properties of metals are

1. Malleability
2. Ductility
3. Electrical conductivity
4. Thermal conductivity
5. Lustre
6. Sonority

Question 12.
How can we change the volume of a gas?
Answer:
On changing the pressure on a gas in a closed container we can change its volume.

Can you tell?

Question 1.
Does water change into vapour the moment we place the vessel on a stove? Does water kept in fridge change at once into ice?
Answer:
No, it doesn’t. Water slowly changes from one state to another.

Question 2.
How do we tell how hot or cold a substance is?
Answer:
A thermometer is used to measure the temperature of the subatance which tell us hot or cold it is.

Question 3.
How will you identify the following

Question i.
A glass: Is it made of plastic, steel or glass?
Answer:
Glass is made of glass as it is transparent.

Question ii.
A rod: Iron or aluminium.
Answer:
A rod is made of iron as it is heavy.

Question iii.
A door: Wooden or glass?
Answer:
A door is wooden as it is opaque.

Question iv.
A white powder: Salt or chalk powder?
Answer:
If powder dissloves in water it is salt and if it does not dissolves in water it is chalk.

Maharashtra State Board Class 7 Science Solutions Chapter 11 Cell Structure and Micro-organisms

Class 7 Science Chapter 11 Cell Structure and Micro-organisms Textbook Questions and Answers

1. Answer the following questions.

Question a.
What is a cell?
Answer:
The cell is the fundamental, structural and functional unit of living organism.

Question b.
Name the different organelles in a cell.
Answer:
The nucleus, endoplasmic reticulum, Golgi bodies, lysosomes, mitochondria, vacuoles, plastids, chloroplasts are the different organelles in a cell.

Question c.
What are micro-organisms?
Answer:
The organisms which cannot be seen with our eyes but can only be observed under a microscope are called micro-organisms.

Question d.
Which are the different types of micro-organisms?
Answer:
Algae, fungi, bacteria, protozoa and viruses are various types of micro-organism. Some are unicellular and others are multicellular. Some of them are useful and some are harmful.

2. Fill in the blanks with the proper word.

Question a.
The organelle called the ……………. is present in the plant cells only.
Answer:
chloroplasts

Question b.
Garbage is converted into ……….. by microorganisms.
Answer:
fertilizer

Question c.
In the cell, photosynthesis is carried out with the help of …………… .
Answer:
chloroplast

Question d.
An electron microscope is necessary for the study of ……………… .
Answer:
micro-organism

Question e.
The process of preparing their own food in presence of sunlight and chloroplast by plants cells is known as ……….. .
Answer:
photosynthesis.

3. What is the difference between us?

Question a.
Plant cell and animal cell.
Answer:

Question b.
Prokaryotic cell and Eukaryotic cell
Answer:

4. Sketch and describe in your on words, the plant cell and animal cell.

Question a.
Sketch and describe ¡n your on words, the plant cell and animal cell.
Answer:
There are two types of cell-animal cells and plant cells. These cells contain various types of membrane beyond cell-organelles. Plant cells have a definite shape due to the presence of cell wall. Besides, unlike animal cells, plant cells contain single large vacuole. All these cells are known as eukaryotic cells. It cell has four main parts: the cell wall, cell membrane, cytoplasm and cell organelles.
1. Cell wall: The cell wall is the outermost covering of a cell. It is present only in plant cells.

2. Plasma membrane: The plasma membrane, also called the cell membrane, is a kind of thin covering, (a) It is extremely delicate and flexible, (b) It is the outermost covering of animal cells.

3. Cytoplasm: The liquid part in the cell, present around the nucleus is called cytoplasm, (a) It occupies the space between the plasma membrane and nucleus, (b) Cell organelles are scattered in the cytoplasm.

4. Cell organelles: These mainly include the nucleus, endoplasmic reticulum, Golgi bodies, lysosomes, mitochondria, vacuoles, plastids etc.

Plant cells contain chloroplasts.
(a) The nucleus is the most important organelle of the cell, (b) There is a porous double membrane around it. (c) The nucleus controls all functions of the cell, (d) The endoplasmic reticulum is a sprawling net-like organelle. Its function is to make necessary changes in the proteins produced by ribosomes and send them to the Golgi bodies, (e) Golgi bodies are made up of several flat sacs. Their function is the proper distribution of proteins.

(f) Mitochondria and plastids are organelles with double outer coverings, (g) As mitochondria produce energy, they are called the powerhouses of the cell, (h) The chloroplasts in plant cells carry out the function of photosynthesis, (i) Vacuoles help to throw out waste products of the cell, (j) Vacuoles in animal cells are small whereas there is only one large vacuole in a plant cell.

5. Explain the uses and the harmful effects of micro-organisms.

Question a.
Explain the uses and the harmful effects of, micro-organisms.
Answer:
Micro-organisms which are helpful are called useful micro-organisms.
Uses:
1. Micro-organisms present in nodules of leguminous plants, convert atmospheric nitrogen into its compounds and these compounds help to increase the soil fertility and protein content in the soil.

2. Some micro-organisms are useful in process of fermentation, making the food easily digestible and more nutritious. For producing milk products like butter, buttermilk, cheese, paneer, etc.

3. Microbes present in soil, dung etc. decompose garbage and convert into manure of best quality and surrounding is kept clean.

4. Microbes are also useful for sewage disposal. They help in decomposition of organic compounds in it.
5. Microbes are used in production of vaccines.

6. Microbes are also used in processes like tanning of skin, production of ropes and strings, from agave.
7. Some microbes use oil for their growth. Such microbes are used to clear a layer of oil floating on the surface of an ocean or lake formed due to leak or spill.

8. Farm waste, human urine and faeces, wet garbage etc. is collected and used in a biogas plant to produce biogas and fertilizer.

Harmful effects:
1. Disease producing micro-organisms are called pathogens, they are harmful micro-organisms.

2. Fungus grows on moist food, and microbes release enterotoxins into the food. Such toxins spoil the foods. Eating such spoiled food causes food poisoning i.e. loose motions and vomiting.

3. Pathogens may be present in water bodies contaminated with sewage, and dirt from surroundings, in food with flies sitting on it. If such contaminated food or water is consumed, we may fall ill with diseases like amoebiasis, typhoid, cholera, hepatitis, gastro, etc.

4. Pathogens are released in the air by a person having infection of the respiratory, sneezes or coughs. A healthy person may get infected by pathogens on breathing in the same air and contract diseases like common cold, cough, diphtheria, pneumonia, tuberculosis, etc.

5. Microbes that cause diseases like malaria, dengue, elephantiasis, yellow fever, chikunguniya, zike
fever etc. gain entry into the human body through the bite of a female mosquito.

6. Give reasons.

Question a.
Diseases spread on a large scale during periods of heavy rainfall and floods.
Answer:

1. Due to floods there is shortage of clean, safe drinking water.
2. It gets contaminated with sewage and dirt having disease causing pathogens, causing disease of alimentary canal, typhoid, cholera, dysentery.
3. Due to stagnant water, many mosquitoes breed on it and cause diseases like malaria, dengue, etc.

Question b.
There is a possibility of food poisoning if we eat stale food.
Answer:

1. Fungus grows quickly on moist and stale food. Micro-organisms grown on the food release toxic materials like enterotoxin into the food.
2. Such toxins spoil the food.
3. Eating such spoiled food may cause loose motions and vomiting. So, we should eat food which is freshly prepared.

Question c.
Soil is turned over during tilling.
Answer:

1. Tilling is done to loosen the soil in initial agricultural practice.
2. Loose soil allows the penetration of roots of the plant.
3. By turning of soil, it allows uniform mixing of manure and fertilizer.
4. It increases the fertility of soil. Seeds also germinate easily in aerated soil. Hence, soil is turned during tilling.

Question d.
Fungus grows quickly in moist or humid condition.
Answer:

1. Fungus needs water and moisture for its growth.
2. Humidity brings about spore germination and the fungus is able to grow and reproduce quickly in moist or humid condition.

Question e.
A refrigerator is used in almost every home.
Answer:

1. Refrigerator is used to keep food item in healthy condition and to keep them fresh.
2. If the food items are kept outside, they spoil very fast due to growth of micro-organisms and they make food spoiled and harmful.
3. The optimum temperature for the growth of micro-organism is 15°C to 35°C.
4. In refrigerator the temperature is kept very low. So, the food is preserved in refrigerator.

Question f.
Bread rises during baking.
Answer:

1. The process of fermentation is used in baking, for example, in making bread. Yeast is added to make the dough rise.
2. The fermentation is a chemical process of conversion of one type of carbon compound into another type of carbon compound by the action of micro-organisms.
3. Heat is generated in this process. Carbon dioxide (CO₂) and some other gases are released.
4. These gases cause an increase in volume so the bread dough rises.

Question g.
Fodder is soaked in water before offering to cattle.
Answer:

1. In dry fodder only some part of it is useful for cattle and rest is wasted.
2. When fodder is soaked in water, it sprouts.
3. So, to make the fodder more nutritious and more easy to digest it is soaked in water before offering to cattle.

7. When will you use a simple microscope and when a compound microscope?

Question a.
When will you use a simple microscope and when a compound microscope?
Answer:

1. I will use a simple microscope to magnify the objects and to see the growth of a fungi or mucor on a piece of moist bread.
2. I will use a compound microscope in Research Laboratory and high school science lab to observe micro-organisms which we are not able to see with our naked eye.

Project:

Question 1.
Visit a bakery in your area, collect information about the process of manufacture of their products and make one of them at home.

Class 7 Science Chapter 11 Cell Structure and Micro-organisms Important Questions and Answers

Fill in the blanks and rewrite the sentences:

Question 1.
………… is the fundamental, structural and functional unit of living organism.
Answer:
Cell

Question 2.
The four main parts of the plant cell are …………, …………, ………… and ………… .
Answer:
cell wall, cell membrane, cytoplasm, cell organelle

Question 3.
Plant cell contains ………… which carry out the process of photosynthesis.
Answer:
chloroplast

Question 4.
…………… are called the power houses of the cell.
Answer:
Mitochondria

Question 5.
The outermost covering of plant cell is …………. .
Answer:
cell wall

Question 6.
The outermost covering of animal cell is ………….
Answer:
plasma membrane

Question 7.
The ………… is the most important organelle of the cell.
Answer:
nucleus

Question 8.
………… is a national movement started several years ago to increase awareness about public hygiene and personal hygiene.
Answer:
Swach Bharat Abhiyan

Question 9.
The body temperature of a healthy human being is about ………… .
Answer:
37°C

Question 10.
Micro-organisms use food stuffs for their own nutrition and release toxic materials called ………. .
Answer:
enterotoxins

Name the following:

Question 1.
An instrument used to observe cells.
Answer:
Microscope

Question 2.
I control the function of a cell.
Answer:
Nucleus

Question 3.
I am like a policeman. I do not allow anything and everything to get in and out of the cell.
Answer:
Cell membrane

Question 4.
Outermost layer of the plant cell.
Answer:
Cell wall

Question 5.
Outermost layer of the animal cell.
Answer:
Cell membrane

Question 6.
I am the jelly like substance containing all the organelles.
Answer:
Cytoplasm

Question 7.
I contain thread like structures called chromosome.
Answer:
Nucleus

Question 8.
Which part of the cell contain organelles.
Answer:
Cytoplasm

Question 9.
The unit of measurement used for expressing dimension, size of the cell.
Answer:
Nanometer, micrometer

Question 10.
The power house of the cell.
Answer:
Mitochondria

Question 11.
Largest organelle in the plant cell.
Answer:
Vacuole

Question 12.
It is necessary for photosynthesis.
Answer:
Chlorophyll

Question 13.
The living substance in the cell.
Answer:
Cytoplasm

Question 14.
A group of cells.
Answer:
Tissue

Question 15.
Empty structures in cytoplasm.
Answer:
Vacuole

State whether the following statements are True or False. Correct and rewrite the false statement:

Question 1.
Cells can be easily seen with naked eyes.
Answer:
False. We can’t see cells with naked eyes, can be seen under microscope

Question 2.
A single cell can perform all the functions in a unicellular organism.
Answer:
True

Question 3.
Cell wall is present in both plant cells and animal cells.
Answer:
False. Cell wall is present only in plant cell

Question 4.
Vacuoles are not found in plant cell.
Answer:
False. Large vacuole is found in plant cell

Question 5.
Tissue is a group of dissimilar cells.
Answer:
False. Tissue is a group of similar cells.

Question 6.
Unicellular organisms have one celled body.
Answer:
True.

Question 7.
The basic living unit of an organism is an organ.
Answer:
False. The basic living unit of an organism is the cell.

Question 8.
The unit of measurement used for expressing dimension size of the cell is centimetre.
Answer:
False. It is nanometer.

Question 9.
Micro-organism cannot grow in extreme adverse conditions.
Answer:
False. Some micro-organisms can survive in extreme adverse conditions e.g. ocean floor, ice polar region, hot water spring.

Question 10.
Some micro-organisms can grow without oxygen.
Answer:
True

Question 11.
Amoeba has irregular shape.
Answer:
True

Question 12.
The process of fermentation is used for making yogurt from milk.
Answer:
True

Question 13.
Micro-organisms need an optimum temperature of 55°C to 70°C to grow.
Answer:
False. They need temperatures between 15°C to 35°C to grow well.

Question 14.
Cells with membrane bound organelles inside them are called prokaryotic cells.
Answer:
False. Cells with membrane bound organelles inside them are called eukaryotic cells.

Question 15.
Golgi bodies are the power houses of the cells.
Answer:
False. Mitochondria are the power houses of the cell.

Choose the correct word.

Question 1.
Which one of the following terms is not a part of the nucleus?
(a) ribosome
(b) DNA
(c) chromosome
(d) gene
Answer:
(a) ribosome

Question 2.
A suitable term for the various components of cell is.
(a) tissue
(b) cell organelle
(c) chromosome
(d) gene
Answer:
(b) cell organelle

Question 3.
The jelly like fluid substance present in the cells is called.
(a) protoplasm
(b) chromosome
(c) chloroplast
(d) cytoplasm
Answer:
(d) cytoplasm

Question 4.
The units of measurement used for expressing dimension size of the cell are,
(a) centimetre
(b) micrometre
(c) nanometre
(d) metre
Answer:
(c) nanometre, (b) micrometre.

Question 5.
The largest cell in the human body
(a) nerve
(b) muscle
(c) liver
(d) kidney
Answer:
(a) nerve

Question 6.
The barrier between protoplasm and other environment in animal cell
(a) plasma membrane
(b) cell wall
(c) nucleus membrane
Answer:
(a) plasma membrane

Question 7.
The term cell wall is given by
(a) Leeuwenhoek
(b) Robert Hooke
(c) Fleming
Answer:
(b) Robert Hooke

Question 8.
The cell theory was proposed by.
(a) Watsonar Cricks
(b) Schleiden
(c) Schwann
(d) Mengal Morgan
Answer:
(b) Schleiden, (c) Schwann.

Question 9.
Which of the following features will help you in distinguishing a plant cell from an animal cell.
(a) cell wall
(b) cell membrane
(c) mitochondria
(d) nucleus
Answer:
(a) cell wall

Question 10.
The gas released during the preparation of bread,
(a) O₂
(b) CO₂
(c) nitrogen
(d) sulphur oxide
Answer:
(b) CO₂

Question 11.
The structural-functional unit of life is called.
(a) cell
(b) tissue
(c) organ
(d) organism
Answer:
(a) cell

Question 12.
Which organelle is called power house of the cell?
(a) centrosome
(b) lysosome
(c) plastid
(d) mitochondria
Answer:
(d) mitochondria

Question 13.
Living substance of cell is called.
(а) cytoplasm
(b) protoplasm
(c) nucleus
(d) chromosome
Answer:
(а) cytoplasm

Give scientific reasons:

Question 1.
Mitochondria are called the power houses of the cell.
Answer:

1. Mitochondria are tiny organelles inside the cells that are involved in releasing energy from food.
2. This process is known as cellular respiration.
3. It is for this reason that mitochondria are often referred to as the power houses of the cell.

Question 2.
A compound microscope is used for observing cells.
Answer:

1. Cell are extremely minute in size.
2. We cannot see cells with naked eye.
3. An object when kept on a glass slide is magnified many times by the lenses of this microscope.
4. Hence, compound microscope is used for observing cells.

Question 3.
Cells are the basic structural units of living organism.
Answer:

1. Cells are the smallest unit from which a living organism is made.
2. A cell contains all the necessary structures which are required to carry out various biological processes.
3. A group of cells makes a tissue, which further makes an organ and many organs together make an organ system and finally organism. Thus, the cells are the basic structural units of living organism.

Answer the following in short:

Question 1.
What is a vaccine?
Answer:
Vaccine is a live micro-organism which is weak but in a very small amount, and is injected into a person so that antibodies are produced against that micro-organism.

Question 2.
What are the similarities between the Plant cell and Animal cell?
Answer:
They both have cell membrane, cytoplasm, nucleus, ribosomes, golgi bodies, mito-chondria, vacuoles and chromosomes.

Question 3.
What do micro-organisms need for growth?
Answer:
Micro-organisms need soil, water and decaying material. Temperature suitable for microbial growth is 15 to 35°C moist, humid and warm climate.

What is the difference between us:

Question 1.
Simple microscope and Compound microscope.
Answer:

Answer in details:

Question 1.
Explain the functions of organelles in a cell.
Answer:
1. Functions of cell wall: It consist of cellulose. It is present in plant cell only. It is a protective layer outside the cell membrane. It provides structural support and protection.

2. Function of cell membrane: It controls the movement of substances in and out of the cell. It protect the cell from its surrounding.

3. Function of cytoplasm: It is the jelly like liquid, it occupies space between cell membrane and nucleus. All the organelles are scattered in it.

4. Function of Nucleus: It is the brain of the cell. It directs all cell activities, and contains genetic material called chromosomes made of DNA.

5. Function of mitochondria: It is the power house of cell. It produces energy in the form of ATP from the food.

6. Vacuoles: It is the largest organelle in the plant cell surrounded by membrane. It holds material and waste. It maintains proper pressure. It helps to throw out waste products of cell.

Explain:

Question 1.
Ram ate chaat from a street hawker, when he reached home he fell ill and complained of stomach ache. What could be the reason?
Answer:

1. he chaat Ram ate from a street hawker must be contaminated with harmful micro-organism due to dirty water used in it or stale potato used in it.
2. Toxins are produced by micro-organisms in food.
3. Ram ate that and suffered from food poisoning.

Question 2.
With the help of diagram describe Prokaryotic cell.

Answer:

1. Prokaryotic cell do not have well-defined nucleus.
2. The plasma membrane, cytoplasm and nucleoid are the only components.
3. The prokaryotic cells have smaller ribosomes compared to eukaryotic cells.
4. Bacteria and blue green algae are examples of prokaryotic cell.

Question a.
Draw neat and labelled diagram of plant cell.
Answer:

Question b.
Draw neat and labelled diagram of animal cell.
Answer:

Name the types of cells shown in the diagrams.

Question 1.

Answer:

(a) A fat cell
(b) A nerve cell
(c) A sperm cell
(d) Spirogyra
(e) Red Blood cells

Try this:

Answer the following questions:

Question 1.
Keep a moistened piece of bread or bhakari in a closed box. What will you observe after 3-4 days?
Answer:

1. I will observe growth of fungus or mucor. White cotton like layer or black spots.
2. As we know fungus grows in presence of moisture.

Question 2.
Observe a drop of muddy water or water from a stagnant puddle, under the compound microscope.
Answer:

1. We will observe, living things, micro-organism, bacteria, fungi.
2. It will be swarming withbacteria,paramoecium, amoeba, ciliated bacteria and protozoa, etc.

Question 3.
Take a drop of yoghurt or buttermilk on a glass slide and observe it under a compound microscope.
Answer:

1. I will see Lactobacillus rod shapted bacteria and streptococcus spherical shape bacteria which may be in clusters.
2. Lactobacillus use lactose present in the milk and produce lactic acid which gives tangy taste to yoghurt.

Find out:

Answer the following questions:

Question 1.
Which diseases do micro-organism cause in plants and animals?
Answer:
Diseases caused by micro-organism in plants and animals are:

Question 2.
Why are infants vaccinated according to fixed time schedule?
Answer:
Vaccination is done to protect the child against diseases.
1. If a baby is vaccinated by true vaccine schedule, that baby will have immunity to over 14 diseases by the age of two. With the recommended schedule, babies visit their doctor 5 times in the first 15 months and receive protection against upto 14 diseases in as little as 18 shots.
2. We immunize children so young against these diseases because infancy is the time period that kids are most vulnerable to life threatening diseases.
3. It is not advisable to skip or delay vaccines as this will leave the child vulnerable to disease for a longer period of time.

Can you tell?

Answer the following questions:

Question 1.
Observe cells from various parts of plants like leaves, bark, root tips, etc.
Answer:
Question a.
Are the cells that you observed, all alike?
Answer:
No, all cells do not look alike, each one has different shape and size.

Question b.
What are their shapes?
Answer:

1. The cells of leaves, show a green pigment because of chloroplast.
2. The shape of the cell may be spherical or polygonal.
3. The shape of root tips are oval or polygonal and the cells of back are hexagonal in shape.

Question 2.
Observe the roots of the pea, bean and fenugreek plants. What could be the functions of the nodules on their roots.
Answer:

1. Micro-organisms are present in the root nodules.
2. They fix the atmospheric nitrogen and make it available for plants.

Question 3.
What happens if clothes remain damp in the rainy season?
Answer:

1. During rainy season the humidity in the air is quite high and also.
2. Due to presence of moisture in clothes it becomes breeding ground for fungus.
3. It is the favourable condition for growth of fungus.
4. We can see white cotton like growth of fungus on clothes.

Question 4.
What are the black or white spots sometimes seen on gunny bags?
Answer:
These spots are the growth of many microbes such as fungi, mucus, mold, etc.

Question 5.
Why are leather articles like purses, wallets, belts, footwear always polished before storing away?
Answer:
They are polished so as to protect them from the growth of fungus.

1. Polish creates a layer of wax on them so that moisture cannot enter from atmosphere.
2. It prevents the growth of fungus, which damages the leather.

Question 6.
What is the powdery material found on old currency notes or old rubber or paper?
Answer:

1. The powdery material is the spores of fungi.
2. All the materials like gunny bags, cotton clothes, paper, rubber, etc. are plant products and leather is an animal product.
3. In a humid atmosphere, fungi and some other micro-organisms grow on these articles and spoil or damage them.

Question 7.
Why children are vaccinated?
Answer:

1. A vaccine is produced in a laboratory with the help of microbes, that gives immunity against particular diseases.
2. Vaccine is actually a live micro-organism which is weak.
3. When injected into a person in small amount, antibodies are produced.
4. It increases the resistance power against the disease produced by that micro-organism. So, the possibility of contracting that disease is greatly reduced.

Question 8.
Try this and answer the following questions:

Question a.
Did the garbage in pot B remain unchanged.
Answer:

1. Yes, the garbage in pot B remained unchanged because micro-organisms need nutrients for their growth.
2. In pot B there was no medium for growth of micro-organisms.

Question b.
Where did the garbage in pot ‘A’ disappear? Why?
Answer:

1. Microbes present in soil, dung, etc. decompose the garbage to obtain food material.
2. As a result garbage is soon converted into manure of the best quality and our surroundings are kept clean.

Question 9.
What does your mother do to make yoghurt from milk?
Answer:

1. Few drops of yoghurt or buttermilk are mixed with lukewarm milk and it is kept at room temperature for 8-10 hours.
2. Microbes present in the drops of yoghurt quickly multiply and the milk gets converted into yoghurt. This is a process of fermentation.

Question 10.
Who discovered the process of fermentation?
Answer:

1. Louis Pasteur established that fermentation is initiated by living organisms.
2. It involves yeast microbes, breaking down molecules of complex carbohydrates into simple sugar, alcohol and CO₂.

Use your brain power!

Answer the following questions:

Question 1.
How will you know that a foodstuff is spoilt?
Answer:

1. When the food is kept for a long time it allows the growth of bacteria and fungi.
2. We can see the white layer of bacterial or fungal growth on it, it causes a typical odour, or smell, and also the food tastes sour due to presence of enterotoxins produced by fungi in the food.

Question 2.
What precautions will you take while purchasing food? Why?
Answer:

1. We will see the expiry date. If the food is kept for a long period of time, it may allow the growth of many microbes which can cause disease or food poisoning.
2. We will check for any fungal growth, any white or black spots on it.

Question 3.
Why do food poisoning incidents occur during marriage or other community feasts?
Answer:
1. During marriage feast, food is prepared in very large quantity and food may not be properly washed or if it is cooked with water contaminated, with sewage or dirt which has many disease causing microbes, or the people handling the food may be having dirty hands

2. Also the utensils used for cooking and storing food may be dirty, contaminated with dirt and may produce microbes. The consumption of such food is responsible for food poisoning.

Question 4.
How do the cells acquire definite shapes?
Answer:
The cells acquire definite shapes due to the presence of cell wall.

Question 5.
How are cells protected?
Answer:

1. Plant cells are protected due to presence of cell wall.
2. Animal cells are protected by the double plasma membrane.

Question 6.
What are the needs of cells?
Answer:

1. The most important things for a cell are oxygen and glucose.
2. Cell uses these during process of glycolysis and makes ATP which is energy source.

Question 7.
Can the point of a needle accommodate micro-organism?
Answer:
Yes, they are smaller than the point of a needle.

Question 8.
Why should dry and wet waste be collected separately?
Answer:

1. Dry waste consist of plastic, glass, metals, paper, etc. It is easier to segregate dry waste so that it is easier for treatment and recycling of waste.
2. Wet waste consists of organic matter. Wet garbage is converted into manure of the best quality and surroundings are kept clean.

Question 9.
Why is yoghurt mixed in the batter or dough for making rava-idli, butter naan?
Answer:

1. The microbes present in yoghurt are allowed to grow in batter or dough.
2. They break down these substances producing new compound and gases are released as they grow and multiply in them which allows the batter, dough to rise.
3. This process is called fermentation.
4. This makes the food soft and nutritious.

Question 10.
How do preparation like yoghurt, idli, dosa become easy to digest?
Answer:
Fermentation does detoxification and splits complex carbohydrates and proteins into simple ones. Thus, making it easy to digest.

Question 11.
What is the co-relation between the normal body temperature of humans which is 37°C and the optimum temperature for the growth of micro-organism, 15 °C to 35 °C?
Answer:

1. Each micro-organism needs a specific environment for growth and reproduction.
2. Optimum temperature for the growth of micro-organism is 15°C to 35°C.
3. Normal body temperature of human body is 37°C. At that temperature micro-organism can not grow and cause disease.

Question 12.
How do micro-organism survive the adverse conditions?
Answer:

1. During adverse conditions micro-organisms form a thick covering around themselves and stop their life processes.
2. On return of favourable conditions they come out of the protective covering and continue their life processes.

Maharashtra State Board Class 7 Science Solutions Chapter 7 Motion, Force and Work

Class 7 Science Chapter 7 Motion, Force and Work Textbook Questions and Answers

1. Fill ¡n the blanks with the proper words from the brackets.
(stationary, zero, changing, constant, displacement, velocity, speed. acceleration, stationary but not zero. inc reuses)

Question a.
If a body traverses a distance in direct proportion to the time, the speed of the body is ……………… .
Answer:
constant

Question b.
If a body is moving with a constant velocity, its acceleration is ……………… .
Answer:
zero

Question c.
……………. is a scalar quantity.
Answer:
Speed

Question d.
…………….. is the distance traversed by a body in a particular direction in unit time.
Answer:
Velocity

2. Observe the figure and answer the questions.

Sachin and Sarneer started on a motorbike from place A, took the turn at 13, did a task at C, travelled by the route CD to D and then went on to E. Altogether, they took one hour for this journey. Find out the actual distance traversed by them and the displacement from A to E. From this, deduce their speed. What was their velocity from A to E in the direction AE’? Can this velocity be called average velocity?

Question a.
Observe the figure and answer the questions

Sachin and Sarneer started on a motorbike from place A, took the turn at 13, did a task at C, travelled by the route CD to D and then went on to E. Altogether, they took one hour for this journey. Find out the actual distance traversed by them and the displacement from A to E. From this, deduce their speed. What was their velocity from A to E in the direction AE’? Can this velocity be called average velocity?
Answer:
1. Actual distance = \(\overline{\mathrm{AB}}\) + \(\overline{\mathrm{BC}}\) + \(\overline{\mathrm{CD}}\) + \(\overline{\mathrm{DE}}\) = 3 + 4 + 5 + 3
Actual distance = 15 km

2. Displacement = \(\overline{\mathrm{AB}}\) + \(\overline{\mathrm{BD}}\) + \(\overline{\mathrm{DE}}\)
= 3 + 3 + 3
Displacement = 9 km

3. Speed = \(\frac{\text { Distance travelled }}{\text { Total time }}\)
Distance = 15 km = 15 × 1000 = 15000 m
Time = 1 hr = 1 × 60 × 60 = 3600 sec.
s = \(\frac{15000}{3600}\) or s = \(\frac{15 \mathrm{~km}}{1 \text { hour }}\) = 15km/hour
= 4.16 m/sec. or 15 km/hour

4. Velocity = \(\frac{\text { Distance travelled }}{\text { Total time }}\)
Displacement = 9 km = 9 × 1000 = 9000 m
Time = 1 hr = 1 × 60 × 60 = 3600 sec
V = \(\frac{9000}{3600}\) or V = \(\frac{9 \mathrm{~km}}{1 \text { hour }}\) = 9 km/hour
= 2.5 m/sec. or 9 km/hour

5. Yes, this velocity can be called as average velocity.

3. From the groups B and C, choose the proper words, for each of the words in group A.

Question a.
From the groups B and C, choose the proper words, for each of the words in group A.

Answer:

4. A bird sitting on a wire, flies, circles around and comes back to its perch. Explain the total distance it traversed during its flight and its eventual displacement.

Question a.
Answer:
The total distance the bird has traversed is the length of the distance covered by circling, but the eventual displacement are the bird is zero as its initial and final position are one and the same.

5. Explain the following concepts in your own words with everyday examples: force, work, displacement, velocity, acceleration, distance.

Question a.
Explain the following concepts in your own words with everyday examples: force, work, displacement, velocity, acceleration, distance.
Answer:
1. Force: The interaction that brings about the acceleration is called force.
e.g: An ox is pulling a cart, applying brakes to a bicycle, lifting heavy iron object with a crane.

2. Work: When an object is displaced by applying a force on it, work is said to be done.
e.g: A bucketful of water is to be drawn from a well and taken to the home by walking from well to home.

3. Displacement: The minimum distance
traversed by a moving body in one direction from the original point to reach the final point is called displacement.
e.g: A rolling of a ball from point A to point B in the same direction.

4. Velocity: Velocity is the distance traversed by a body in a specific direction in unit time.
e.g: A truck is covering a distance of 40km from A to D in a straight line in 1 hour.

5. Acceleration: It is change in velocity per second. It can be deduced.
Acceleration = \(\frac{\text { Change in velocity }}{\text { Time taken for change }}\)
e.g:

(i) In the above example a truck covered the distance AB at velocity of 60 km/hr, BC at 30 km/hr and CD at 40 km/hr. (ii) It means that the velocity for the distance CD is greater than the velocity for the distance BC. (iii) From the number of seconds required for this change in velocity to take place, the change in velocity per second can be deduced. This is called acceleration (iv) Distance: The length of the route actually traversed by a moving body irrespective of the direction is called distance.
e.g: Ranjit travelled 1km. from his home to school.

6. A ball is rolling from A to D on a flat and smooth surface. Its speed is 2 cm/s. On reaching B, it was pushed continuously up to C. On reaching D from C, its speed had become 4 cm/s. It took 2 seconds for it to go from B to C. What is the acceleration of the ball as it goes from B to C.

Question a.
A ball is rolling from A to D on a flat and smooth surface. Its speed is 2 cm/s. On reaching B, it was pushed continuously up to C. On reaching D from C, its speed had become 4 cm/s. It took 2 seconds for it to go from B to C. What is the acceleration of the ball as it goes from B to C.

Answer:
As its initial and final positions are one and the same.
Initial Velocity = 2 cm/s.
Final Velocity = 4 cm/s
Time taken for the change in velocity from B to
D = 4 cm/s – 2 cm/s = 2 cm/s

7. Solve the following problems.

Question a.
A force of 1000 N was applied to stop a car that was moving with a constant velocity. The car stopped after moving through 10m. How much is the work done?
Answer:
Force (F) = 1000 N
displacement (s) = 10m
work done (W) = ?
W = Fs
= 1000 × 10
W = 10,000 Joule

Question b.
A cart with mass 20 kg went 50 m in a straight line on a plain and smooth road when a force of 2 N was applied to it. How much work was done by the force?
Answer:
Force (F) = 2 N
Displacement (s) = 50 m
Work done (W) = ?
W = Fs
= 2 × 50
W = 100 Joule

Project:

Question a.
Collect information about the study made by Sir Isaac Newton regarding force and acceleration and discuss it with your teacher.

Class 7 Science Chapter 7 Motion, Force and Work Important Questions and Answers

Fill in blanks:

Question 1.
Displacement is a …………. quantity.
Answer:
vector

Question 2.
The …………. of an object can change even while it is moving along a straight line.
Answer:
velocity

Question 3.
The …………. velocity can be different at different times.
Answer:
instantaneous

Question 4.
Change in velocity per second is called …………. .
Answer:
acceleration

Question 5.
The interaction that brings about the acceleration is called …………. .
Answer:
force

Question 6.
The scientist …………. was the first to study force and the resulting acceleration.
Answer:
Sir Isaac Nezvton

Question 7.
Ability to do work is called …………. .
Answer:
Energy

Question 8.
W = …………. × S.
Answer:
F

Question 9.
Unit of work is …………. and …………. .
Answer:
Joule, erg

Question 10.
Unit of force is …………. and …………. .
Answer:
Newton, dyne

Question 11.
Force is a …………. quantity.
Answer:
vector

Question 12.
The velocity at a particular time is called …………. velocity.
Answer:
instantaneous

Question 13.
The …………. of a body is the distance traversed per unit time.
Answer:
speed

Question 14.
Unit of acceleration is …………. and …………. .
Answer:
m/s² and cm/s²

Question 15.
Force is measured by the …………. that it produces.
Answer:
acceleration

Question 16.
Work done by a body with no displacement will be …………. .
Answer:
zero

Say whether True or False, correct the false 1 statements:

Question 1.
Velocity is distance travelled per unit of time.
Answer:
False. Speed is distance travelled per unit of time

Question 2.
In displacement, both distance and direction are taken into account.
Answer:
True

Question 3.
Speed = Distance/time.
Answer:
True

Question 4.
Change in speed per second is acceleration.
Answer:
False. Change in velocity per second is acceleration

Question 5.
Work done depends on the force and the displacement.
Answer:
True

Question 6.
C.G.S. unit of acceleration is m/s².
Answer:
False. C.G.S. unit of acceleration is cm/s².

Question 7.
M.K.S. unit of force is dyne.
Answer:
False. M.K.S. unit of force is Newton

Question 8.
Force is measured by the acceleration that it produces.
Answer:
True

Write the difference between the following:

Question 1.
Speed and Velocity
Answer:

Question 2.
Distance and Displacement
Answer:

Solve the following problems!

Question 1.
A bus travelled 200 km in the first 3 hours and then 100 kms for the next one and a half hours and then 120 kms for the next one and a half hours. What is the average velocity of the bus if it has moved in a straight line for the whole journey.
Answer:

Question 2.
See the diagram and calculate the Distance and Displacement travelled by the body from A to I.

Answer:
Distance travelled =
A → B → C → D → E → F → G → H + I
= 5 + 7 + 6 + 3 + 5 + 4 + 6 + 5
= 41 m
Displacement = A → I in a straight line shortest distance
= 1m

Use your brainpower:

Question 1.
The unit of acceleration is m/s², verify this.
Answer:

Question 2.
Acceleration is a vector quantity. Is force a vector quantity too?
Answer:
Yes, acceleration and force both are vector quantities, because both can be expressed completely only when magnitude and direction are given and the quantity which needs direction and magnitude both is called a vector quantity.

Maharashtra State Board Class 8 English Solutions Chapter 2.2 Nature Created Man and Woman as Equals

Class 8 English Chapter 2.2 Nature Created Man and Woman as Equals Textbook Questions and Answers

Warming Up

A. Study the pictures given on page 30 of the textbook and note the differences :

Answer:
Set (i) In the first panel a boy is going to school while a girl of the same age is doing household chores. In the next panel, both the boy and the girl are going to school.

Answer:
Set (ii) In the first panel, a woman is trudging along balancing pots of water on her head and a baby on her hip. In the next panel, a woman is teaching children at a school.

B. Now write what you observe in the following two pictures:

Answer:
(i) In the first panel a boy and a man are shown sharing the household chores, leaving the women to do other work.
(ii) In the next panel, men and women are working in an office together at an equal level.

C. Which pictures reflect gender equality? Write their numbers.
Answer:
The pictures on the right-hand side of:
(A) and both the pictures of
(B) reflect gender equality.

D. Write down any two slogans on gender equality.
Answer:
(i) Let’s have peace and unity
For all, give equal opportunity.

(ii) Men and women, Are all the same.
Please stop playing, This discrimination game.

1. A. Find from the lesson words/phrases that mean the following:

Question a.
colours …………
Answer:
Hues.

Question b.
a person who writes for newspapers/magazines …………
Answer:
Journalist.

Question c.
make a difference between ………
Answer:
Discriminate.

Question d.
cryover ………
Answer:
Lament

Question e.
explain in detail ………
Answer:
Throw light on.

Question f.
abilities and qualities ……….
Answer:
Potential

Question g.
same availability ……….
Answer:
Equal Access

Question h.
a person who brings about a social/political change …………
Answer:
Activist.

1. B. Pick out five Compound words from the lesson.
Answer:

• anywhere
• household crystal-clear
• courtyard
• reading room
• middle-aged

2. Answer in your own words:

Question a.
Read and write down 5 points which prove that Tomba, (Lanthoi’s father) firmly believes in gender equality.
Answer:
The facts which prove that Tomba firmly believes in gender equality are:

1. Tomba is supportive of Ashang bis activities as a woman’s rights activist.
2. He advocates the cause of women.
3. He does not discriminate between a man’s work and a woman’s work.
4. He shares equally with Ashangbi in doing the household chores like cooking, washing, etc.
5. He tells Lanthoi that the world is still full of inequalities and they have to find a way to bring equality between men and women.

Question b.
In what ways is Ashangbi different from other women of her community?
Answer:
Ashangbi is different from other women of her community:

• she is a woman’s rights activist
• she is a journalist is different

Question c.
What are the provisions in the Declaration of the United Nations, to ensure equality of men and women?
Answer:
The provisions In the Declaration of the United Nations to ensure equality of men and women are:

• equal access to basic social services including health and education.
• equal participation in political and economic decision-making.
• equal reward for equal work, and
• elimination of discrimination and violence against women.

3. Who said to whom and when / why?

Answer:

4. We have studied in previous classes that Pronouns are nords used instead of Nouns.

We also know about Personal Pronouns like I, you, he, she, my, your, his, her, they etc.
There are other words also which are used in place of nouns.
(i) This, that, these, those point to some noun.
For example: ‘Ihi is a kingfisher.’ Those are herons.’ Such Pronouns are called Demonstrative Pronouns.

(ii) Some pronouns not only replace nouns, but also connect two sentences.
For example : Biology is a science. It studies living organisms.’
Biology is a science which / th studies living organisms.
Some other such pronouns are who, whose, whom etc.
They are called Relative Pronouns.

(iii) Some pronouns are used to ask questions.
For example: What is your name?
Which is your coat?
Who is your coach?
The underlined words are Interrogative Pronouns.

Underline the Pronouns in the following sentences and name their types:

Question 1.
What do you want to do?
Answer:
What do you want to do?
What – Interrogative Pronoun
you – Personal Pronoun

Question 2.
It is because of your father that I feel no inequality.
Answer:
It is because of your father that I feel no inequality.
your, I-Personal Pronoun

Question 3.
This is what your topic means.
Answer:
This is what your topic means.
This – Demonstrative Pronoun;
your-Personal Pronoun

Question 4.
She is fascinated by the small trail, which winds up the mountain.
Answer:
She is fascinated by the small trail, which winds up the mountain.
She – Personal Pronoun
which – Interrogative Pronoun

5. Read the following lines. Imagine it is the beginning of an instance you have experienced. Complete the incident using your imagination. Give it u positise ending. I had often noticed that in my neighbour’s family, the son was greatly pampered, but the daughter was treated unfairly. I could not bear this. So one day I decided to ………….

Continue the write-ups with your own ideas, in about 12 – 15 lines.
Answer:
I had often noticed that in my neighbour’s family, the son was greatly pampered, but the daughter, Meera, was treated unfairly. I could not bear this. So one day I decided to do something about it. I knew that as a young girl, I could not go in and give them advice. It had to be done diplomatically. I decided to make a folder of stories of successful women who had scaled wonderful heights and were greatly respected. I also made a list of women entrepreneurs and their lives. It took me a long time to do this, but it also became my project at school and I got guidance from my teacher and my mother. They asked me to make a power-point presentation too, in addition to the folder. After about three months of hard work. my project was complete.

One afternoon, when I knew that Meera’s mother would be alone at home, I took my presentation and my folder. Pretending that I wanted her opinion on my school project, I showed her the entire presentation. My plan was successful. At the end of two anxious hours, Meera’s mother turned round and hugged me. “I get your message,” she said through her tears. “We have been unfair to Meera. We will rectify it immediately. Thanks, dear.”
I don’t know the marks I will get in school for my project, but according to me, it is already in the A+ category. It has made a positive impact. And that’s enough reward for me.

6. Project :
From your school library or internet collect quotations/slogans promoting gender equality. Make decorative posters with pictures of outstanding women or sketches or illustrations of your choice. With permission, put up the posters in your school surroundings.

Class 8 English Chapter 2.2 Nature Created Man and Woman as Equals Additional Important Questions and Answers

Simple Factual Activities:

Question 1.
Make a list of the beautiful natural surroundings of the house.
Answer:

• A small stream of crystal clear water.
• The green mountains
• A stretch of hundreds of acres of fertile land with yellow mustard flowers.
• A garden in front of the house.
• Many kinds of trees bearing flowers of different colours and fruits.
• Fragrant jasmine.

Question 2.
Write down the ways in which Ashangbi is different from other women of her community.
Answer:

Question 3.
What help did Lanthoi need from her mother?
Answer:
Lanthoi was going to speak on the topic ‘God created men and women as equals’ at her school. She wanted to have some discussion with her mother on the topic.

State what kind of sentences the following are:

Question 1.
Tell me what you want to do.
Answer:
Imperative

Question 2.
Will you spare some time to have a discussion with me ?
Answer:
Interrogative

Personal Response:

Question 1.
Do you think that a woman should have a paid job outside the house or stay at home as a full-time homemaker?
Answer:
I think that depends on the woman and the circumstances. If she is qualified and wants to pursue a career, she should do so. If she wishes to stay at home, she should do that. It is important that she should have the freedom to choose and do as she wishes.

Answer in brief:

Question 1.
What did Lanthoi’s father work as?
Answer:
Lanthoi’s father Tomba is a lawyer and a social wrorker, who advocates the cause of women.

Question 2.
What does Ashangbi feel about Tomba’s views on gender equality?
Answer:
Ashangbi is appreciative of Tomba’s view on gender equality.

Complex Factual Activities:

Question 1.
List the ways in which Tomba contributes towards Ashangbi’s success.
Answer:
The ways in which Tomba contributes towards Ashangbi’s success are:

• Tomba is supportive of Ashangbi’s activities.
• He is always proud of his wife and children.
• In times of need, he helps his wife and children.
• He does not discriminate between a man’s work and woman’s work.
• He shares equally with Ashangbi in doing the household chores like cooking, washing, etc.

Question 2.
Describe how mother explained Lanthoi’s topic for her speech at school.
Answer:
Lanthoi’s topic for her speech was ‘God created men and women as equals.’ Ashangbi explained to Lanthoi that God has sent men and women to our earth to share the joys and sorrows of life equally, to share His blessings and to enjoy the bounty of nature equally. Hence, men and women are equals and should be treated as such.

Question 3.
Write down five points which prove that Tomba firmly believes in gender equality.
Answer:
The facts which prove that Tomba firmly believes in gender equality are:

• Tomba is supportive of Ashangbi’s activities as a woman’s rights activist.
• He advocates the cause of women.
• He does not discriminate between a man’s work and woman’s work.
• He shares equally with Ashangbi in doing the household chores like cooking, washing, etc.
• He tells Lanthoi that the world is still full of inequalities and they have to find a way to bring equality between men and women.

Personal Response:

Question 1.
In olden days, men and women had ‘fixed’ roles to play, and ‘fixed’ jobs to do. Do you think there should be a change in this today?
Answer:
Yes, as society changes and progresses we must change the ‘fixed’ roles and ‘fixed’ jobs too. Today, when women are going out, working and adding to the family income, men too should help in the house. Women have learnt to do many jobs which were earlier done only by men. Men too should learn to do jobs which were earlier done only by women.

Write whether the following statements are True or False:

Question 1.
Lanthoi’s grandmother has narrated many stories about brave queens to her.
Answer:
True

Question 2.
Lanthoi found the topic of pioneer women boring.
Answer:
False

Question 3.
Linthoingambi and Kuranganayani were brave kings.
Answer:
False

Question 4.
Lanthoi has a lot of respect for Ashangbi.
Answer:
True

Complex Factual Activities:

Question 1.
Describe how the role of a mother is honoured and praised.
Answer:
The mother is said to be the fountain of love in the family. This bond of love cannot be compared to anything else in the world. Motherhood has been glorified because of this and therefore women accept the challenges in life to become a mother.

Question 2.
Complete the web showing the achievements of modern women.

Answer:

Write the noun forms of the following words:

• know
• qual
• narrated
• brave

Answer:

• knowledge
• equality
• narration/narrator
• bravery

Activities based on Contextual Grammar:

Question 1.
This bond of love Is beyond comparison with anything else in the world.
(Make the sentence negative.)
Answer:
This bond of love cannot be compared with anything else In the world.

Question 2.
Life is not possible without both women and men.
(Make the sentence affirmative.)
Answer:
Life is impossible without both women and men.

Personal Response:

Question 1.
Have you read stories/biographies of successful women? Did you like them?
Answer:
Yes, I have. I have read about Rani Laxmlbal. I have also read short stories and articles about women like Marie Curie, Sudha Chandran, Annie Besant, Mother Teresa, etc. like them and find them motivating.

Write ‘Yes’ or ‘No’:

Question 1.
Lanthoi finally understands what the topic of the symposium means.
Answer:
Yes

Question 2.
Ashangbi satisfies her daughter’s curiosity.
Answer:
Yes

Question 3.
Lanthoi is unsure and nervous about her presentation.
Answer:
No

Question 4.
The United Nations has affirmed that men and women are equals.
Answer:
Yes

Complex Factual Activities:

Question 1.
Write down the provisions in the Declaration of the United Nations to ensure equality of men and women. OR What social justice does the aegis of the United Nations guarantee?
Answer:
The provisions In the Declaration of the United Nations to ensure equality of men and women are:

• equal access to basic social services including health and education.
• equal participation in political and economic decision-making.
• equal reward for equal work, and
• elimination of discrimination and violence against women.

Question 2.
Describe the vision that meets Lanthoi’s eyes when she rushes outdoor.
Answer:
When Lanthoi rushes outdoors, she is welcomed by the bright morning sun. The blue sky and the range of mountains : appear to meet. Lanthoi is fascinated by a small trail which goes winding up the ; distant purple mountain.

Pick out the subject and predicate:

Question 1.
He extends his helping hand to his wife and children and to the society at large.
Answer:
He-subject
extends his helping hand to his wife and children and to the society at large-predicate

Question 2.
Use the word ‘share’ as a noun and a verb in two separate sentences:
Answer:
(i) The wicked brother wanted his share in the property, (noun)
(ii) The poor woman shared the loaf of bread with her children, (verb)

Writing Skills

Read the following lines. Imagine that it is the beginning of an instance you have experienced. Continue the write-up with your own ideas, in about 12-15 lines and complete the incident using your imagination. Give it a positive ending.
I had often noticed that in my neighbour’s family, the son was greatly pampered, but the daughter was treated unfairly. I could not bear this. So one day I decided to ……………..
Answer:
I had often noticed that in my neighbour’s family, the son was greatly pampered, but the daughter, Meera, was treated unfairly. I could not bear this. So one day I decided to do something about it.

I knew that as a young girl, I could not go in and give them advice. It had to be done diplomatically. I decided to make a folder of stories of successful women who had scaled wonderful heights and were greatly respected. I also made a list of women entrepreneurs and their lives. It took me a long time to do this, but it also became my project at school and I got j guidance from my teacher and my mother.

They asked me to make a power-point presentation too, in addition to the folder. After about three months of hard work, my project was complete. One afternoon, when I knew that Meera’s mother would be alone at home, I took my presentation and my folder. Pretending that I wanted her opinion on my school project, I showed her the entire presentation.

My plan was successful. At the end of two anxious hours, Meera’s mother turned round and hugged me. “I get your message,” she said through her tears. “We have been unfair to Meera. We will rectify l it immediately. Thanks, dear.” I don’t know the marks I will get in ; school for my project, but according to me, it is already in the A+ category. It has made a positive impact. And that’s enough reward for me.

Maharashtra State Board Class 7 Science Solutions Chapter 10 Disaster Management

Class 7 Science Chapter 10 Disaster Management Textbook Questions and Answers

1. Find the odd man out:

Question a.
Famine, earthquake, cloudburst, railway accident.
Answer:
Railway accident.

Question b.
Drought, heavy rains/storm, tsunami.
Answer:
Drought.

Question c.
Lava, hot mud, ash, locusts.
Answer:
Locusts.

Question d.
Washing away of crops, attack of pests on crops, volcano, singeing of crops.
Answer:
Volcano.

2. What are the remedial measures for the following calamities?

Question a.
Famine:
Answer:
Following are the remedial measures for famine:

1. Supply food and water to the people those who are dying due to hunger.
2. Give medicines to the people those who are suffering from malnutrition.
3. Government should start helping centres for the people those who are suffering from famine.
4. Give them temporary shelter in some other places where water and food are available.
5. Shift the animals to safer places.
6. Do proper planning so that region doesn’t get famine again and again.
7. Reuse water
8. grow more trees.

Question b.
Lightning strike:
Answer:
Following are the remedial measures for lightning strike:

1. Give immediate treatment to the lightning affected persons so their life can be saved.
2. Keep the people away from the open ground and swimming pool.
3. Provide them proper guidelines to cure for the lightning strike.

Question c.
Storm:
Answer:

1. Supply food, water and medicines to the people
2. Shift them to safe places.
3. Maintain peace, and advice the people not to panic.
4. Give time to time report on T.V. and radio.

Question d.
Cloudburst:
Answer:
Following are the remedial measures for cloudburst:

1. Shift people to safe places with the help of airplane, helicopter and army.
2. Supply them food, clothes, water and medicines.
3. Give time to time weather report.
4. Open more helpline centres.
5. Government should immediately send the help in terms of money and army to the people.

3. True or false? Give reasons for your answer.

Question a.
Information about a forthcoming storm is to be kept secret.
Answer:
False. Information about a forthcoming storm is not to be kept secret because, with this information we can take immediate steps for disaster management. Large scale damage of property and loss of life can be avoided.

Question b.
You should not swim when there is lightning in the sky.
Answer:
True. Lightning carries some electric charges which causes electric current in it. Water catches this current so if any person is swimming pool during lightning in the sky, then there are more chances that lightning may strike in water and the person may die due to it.

Question c.
It is possible to prevent the eruption of a volcano.
Answer:
False. It is not possible to prevent the eruption of a volcano because it is a natural event. However, by means of science and technology, it is possible to predict an eruption in advance and to take immediate steps for disaster management.

Question d.
Heavy rains result in famine.
Answer:
True. Heavy rains result in flood so crops get washed away or damaged in the flood and results in famine.

Question e.
A loud crashing sound follows a lightning.
Answer:
True, Friction and brushing happens between two clouds making them charged and lightning is produced between two clouds or one cloud and earth. The temperature increases and air pressure also increases to high amount and produces a loud sound of thunder.

4. Write answers to the following questions in our own words.

Question a.
What is a tsunami? What gives rise to a tsunami?
Answer:

1. Waves generated by an earthquake or volcano occurring on the ocean floor is called ‘tsunami’. ‘Tsunami’ is a Japanese word which means ‘harbour wave’.
2. As on land, earthquakes and volcanic eruptions occur, at the bottom of the sea, too.
3. If an earthquake occurs at the bottom of ocean, the energy released pushes the water upwards. As a result of this particular type of waves are formed.
4. These waves are not very high near the source, but they start spreading very fast to long distances.
5. The velocity of these waves is 800 to 900 km/hr. When they reach a coastal area, their velocity is reduced, but their height is found to have increased tremendously even to about 30 m. These are tsunami waves.

Question b.
What is cloudburst?
Answer:

1. Sometimes the water coming down from rain clouds does not reach the land in the form of rain. Instead, due to very high temperature near the land, it vaporizes and goes back into the same clouds.
2. As a result the amount of vapour in those clouds becomes very high.
3. Due to rapid condensation, it rains suddenly over a specific and small region at a rate of 100 mm per hour or more. This is known as a cloudburst.

Question c.
Explain the effects of a volcano.
Answer:
Following are the effects of a volcano:

1. The chemical substances such as lava, vapour, hot mud, sulphur etc. get collected on the surface of the earth and thereby mountains and hills are created
2. The atmosphere gets polluted due to the ash and gases ejected by the volcano.
3. Often, it rains as a result of a volcanic eruption.
4. The temperature rises due to hot gases.
5. Forests and settlement get buried under the hot mud.

Question d.
What are the measures to prevent loss of life due to lightning?
Answer:
Following are the measures to prevent loss of life due to lightning:

1. Do not stand on open ground, below a tree, on high location, near an electric pole, near a telephone pole or a tower etc.
2. Do not lean on wire fences around a farm, a compound, a garden or a house.
3. If you are on two-wheeler, a bicycle, a tractor or a boat, get off immediately and go to safe place.
4. Do not gather all together in one place.
5. Take care to keep a distance of 15 feet between any two persons.
6. Do not use plugged in electrical appliances. Do not use a mobile or telephone.
7. Stand on dry wood, a plastic sheet, sack or jute cloth or dry leaves.
8. Keeping your feet together support yourself on the soles of your feet placing your hands on your knees and crouch low.
9. Swimmers and fishermen should immediately come out of the water.
10. A pucca house is the safest place. Find out if there is a lightning conductor on any tall building near your house. If necessary get a lightning conductor fitted on your house.

5. What measures have been taken to deal with calamities such as floods and landslides under the disaster management programme in Maharashtra?

Question a.
What measures have been taken to deal with calamities such as floods and landslides under the disaster management programme in Maharashtra?
Answer:
In Maharashtra, all districts have their own disaster management plan to deal with calamities such as floods and landslides.

1. The plan deals extensively with the emergency, and evacuation measures to be taken up in cases of flood and landslide.
2. The district-level disaster management plan has detailed information about geographical details, population, flood-prone areas, villages and other macro details.
3. Nearly 14 such key departments are engaged in disaster mitigation measures and each one has been assigned a specific task to do at times of natural disasters.
4. The administration is now training master trainers at the district level who in turn will train key persons at village and taluka levels to deal with a natural disaster.
5. The administration through radio jingles, public advertisements and other measures is informing people about how to react at times of flood and landslide.
6. Currently, the Indian Meteorological Department (IMD) gives weather forecast on daily basis and for the next 5 days with advice to farmers on when to start crop sowing and harvesting etc.

6. With reference to disaster management what are the things in your house that you will check?

Question a.
With reference to disaster management what are the things in your house that you will check?
Answer:
With reference to disaster management, we should keep the following things at home and check regularly.

1. Keep proper first aid kit at a handy place.
2. Keep all the electric connections in proper condition.
3. Keep the gas line or tube connection proper.
4. Keep self-powered flashlights and self-powered radios.
5. Keep non-perishable food which will last for a week.
6. Keep a fire extinguisher handy and in proper condition.
7. Keep updated telephone diary which should have emergency phone numbers.

Project:

Question 1.
With the help of the Internet, collect information about the places where a calamity has occurred.

Question 2.
Collect information from the Internet about how cyclonic storms are named.

Class 7 Science Chapter 10 Disaster Management Important Questions and Answers

Fill in the blanks:

Question 1.
………… and ………… disasters are related to each other.
Answer:
Natural manmade.

Question 2.
………… implemented a canal scheme for drinking water in Aurangabad.
Answer:
Malik Ambar.

Question 3.
………… has turned out to be the most famine-affected contents of the world.
Answer:
Asia

Question 4.
The government of India established the ………… in 1976.
Answer:
National Flood Commission

Question 5.
The ………… that occurred in Mumbai on 26th August 2005 was extraordinary and unforgettable.
Answer:
cloudburst.

Question 6.
A cloudburst occurred at ………… on 6th August, 2010.
Answer:
Ladakh (Leh)

Question 7.
About ………… lightning flashes occur per second in the atmosphere.
Answer:
40.

Question 8.
The temperature generated by ………… is higher than that of the sun.
Answer:
lightning

Question 9.
When some substances comes out of the earth’s crust in an eruption and start flowing is called a ………… .
Answer:
volcano

Question 10.
Some islands are created due to the eruption, of ………… in the sea.
Answer:
volcano

Question 11.
………… is a Japanese word which means ‘harbour wave’.
Answer:
Tsunami.

Question 12.
About ………… nations from all over the world are members of the UNDP.
Answer:
177.

Question 13.
………… established a standing international organization UNDP in 1965.
Answer:
United Nations.

Question 14.
………… is celebrated as International Day for Disaster Reduction.
Answer:
13th October

Question 15.
The condition that arises due to long term and severe scarcity of food grains and water is called………. .
Answer:
famine

Can you tell?

Question 1.
Is it possible to prevent the loss of life caused by lightning?
Answer:
Yes, it is possible to prevent the loss of life caused by lightning, by taking precautions.

Question 2.
What should be done to prevent the bunds on a farm from getting washed away in the rainy season?
Answer:

1. Grow more trees near the bunds.
2. Grow grass strips.
3. Make stone lines near the bunds.
4. Use contour ploughing and tillage network method to prevent the bunds on a farm from getting washed away in the rainy season.

Question 3.
Why do we experience water scarcity?
Answer:
Lessor no rain leads to water scarcity.

Question 4.
What causes rain?
Answer:

1. Due to heat of the sun, water from the sea, lake and river gets evaporated and this water vapour is light in weight so it goes higher and higher and forms the cloud.
2. At a certain level the amount of vapour in those clouds becomes very heavy and it burst and rain occurs.

Question 5.
Have you seen a flash of lightning in the sky? When?
Answer:
Students will answer this question based on their experience.

Question 6.
What causes lightning?
Answer:

1. Where air and clouds rub against each other in the sky, the upper part of some clouds on the upper side becomes positively charged and the lower sides become negatively charged.
2. When this negative charge on the bottom of the cloud becomes much larger than the charge on the ground it starts flowing towards the ground in stages.
3. This happens very fast, in much less than a second and heat, light and sound energy are produced along with the electric current.

Use your brainpower!

Answer the following questions:

Question 1.
We should not wait at the foothill while it is raining heavily.
Answer:
During heavy rain there are chances of landslide and flood, so we should not wait at the foothill while it is raining heavily.

Maharashtra State Board Class 6 Science Solutions Chapter 12 Simple Machines

Class 6 Science Chapter 12 Simple Machines Textbook Questions and Answers

1. Classify the following as a lever, a pulley and an inclined plane:
(A wedge, a needle, a staircase, a slide, the wheel of a flagpole, nutcrackers, scissors, an opener, an axe, a crane, a knife)

Question a.
Classify the following as a lever, a pulley and an inclined plane:
(A wedge, a needle, a staircase, a slide, the wheel of a flagpole, nutcrackers, scissors, an opener, an axe, a crane, a knife)
Answer:

2. Fill in the blanks using the proper word and complete the statements.

Question a.
The ………….. in the centre, the ………….. on one side and the on the ………….. other side make a lever of the first order.
Answer:
Fulcrum, load and effort

Question b.
The ………….. in the centre, the ………….. on one side and the ………….. on the other side make a lever of the second order.
Answer:
Load, fulcrum, effort

Question c.
The ………….. in the centre, the ………….. on one side and the ………….. on the other side make a lever of the third order.
Answer:
Effort, fulcrum, load

3. Which machines will you use to do the following work? Write their types.

Question a.
To remove the lid of a tin. Opener Lever of the second order
Answer:

• Work: To remove the lid of a tin.
• Machine: Opener
• Machine: Lever of the second order

Question b.
To lift bricks to the top of a tall building Crane Complex machine
Answer:

• Work: To lift bricks to the top of a tall building
• Machine: Crane
• Machine: Complex machine

Question c.
To cut vegetable Knife Wedge – Simple machine
Answer:

• Work: To cut vegetable
• Machine: Knife
• Machine: Wedge – Simple machine

Question d.
To draw water from a well Pulley Simple machine
Answer:

• Work: To draw water from a well
• Machine: Pulley
• Machine: Simple machine

Question e.
To hold a papad for roasting it. A pair of tongs Lever of the third order
Answer:

• Work: To hold a papad for roasting it.
• Machine: A pair of tongs
• Machine: Lever of the third order

4. Write the answers to the following questions in your own words. 

Question a.
What is meant by a simple machine?
Answer:

1. Machines which have only one or two parts and a simple and easy structure are simple machines.
2. Example: the bottle opener, nail cutter.
3. Simple machines can be handled easily.
4. We use many simple machines in our day to day life.

Question b.
Mention the advantages of using a machine.
Answer:

1. Machines, simple or complex, are used to get more work done in less time and with less effort.
2. Machines are used to accomplish certain tasks more easily.
3. Use of simple or complex machines depends upon the task to be carried out and the time and the efforts required to do it.

Question c.
What is meant by a complex machine?
Answer:

1. Complex machines have many parts which carry out many processes for completing a task.
2. For this purpose the parts are joined to one another.
3. Therefore, these machines are called complex machines.
4. Some of the parts of such complex machines are actually simple machines.
5. The structure of complex machine is complicated.

Question d.
What is a lever? How is the order of the lever determined?
Answer:

1. Lever is a simple machine made up of 3 parts: Load, effort and fulcrum.
2. Order of the lever are determined on the position of the effort, the fulcrum and the load.

5. Why is this so?

Question a.
Traveller’s bags have wheels.
Answer:

1. Combination of wheel and axle is a simple machine.
2. When the axle starts rotating due to force applied, the wheel fitted to it also starts rotating.
3. This makes easier for travellers to carry heavy load.
4. Instead of lifting heavy bag, to drawing it on wheels require less energy. Therefore, traveller’s bag have wheels.

Question b.
Machines have to be maintained.
Answer:

1. Parts of machines rub against one another when they are used.
2. Soiled, dusty parts create more friction. Some parts are affected by the weather, rust and corrosion.
3. Machines get damaged or become useless due to such wear and tear. Hence to avoid this, machines should be maintained properly to keep them in good working condition.

Question c.
A bicycle is said to be a complex machine.
Answer:

1. Bicycle has a complicated structure.
2. Bicycle has many parts which carry out many processes for completing a task.
3. Many parts of bicycle such as pedals, wheels, axle, handle are actually simple machines.
4. The parts of a bicycle are joined to one another – making it a complex machine.

6. Name the levers mentioned in the following passage. Identify the fulcrum, load and effort of each and say which type of lever it is.

Ravi and Savita sit on a sea-saw in a garden. In the mean time, a gardener is trimming trees in the garden. He puts the leaves and other garbage in the wheelbarrow. Later, Ravi gets thirsty and he buys lemon sherbet. The sherbet seller cuts the lemon and squeezes it using a lemon squeezer. He puts small pieces of ice in the glass with the help of the tongs.

Question a.
Name the levers mentioned in the following passage. Identify the fulcrum, load and effort of each and say which type of lever it is.

Ravi and Savita sit on a sea-saw in a garden. In the mean time, a gardener is trimming trees in the garden. He puts the leaves and other garbage in the wheelbarrow. Later, Ravi gets thirsty and he buys lemon sherbet. The sherbet seller cuts the lemon and squeezes it using a lemon squeezer. He puts small pieces of ice in the glass with the help of the tongs.
Answer:
Levers:

1. See – saw – lever of the first order.
   Load – fulcrum – effort.
2. Wheelbarrow – lever of the second order.
   Fulcrum – load – effort.
3. Lemon squeezers – lever of the second order.
   Fulcrum – load – effort.
4. Tongs – lever of the third order.
   Fulcrum – effort – load.

Activity:

Question 1.
Make a list of the various machines used in your home and neighborhood and write their types.

Question 2.
Go to a bicycle repair shop, observe how a bicycle is repaired, and note down the information.

Class 6 Science Chapter 12 Simple Machines Important Questions and Answers

Fill in the blanks.

Question 1.
Simple machines can be handled ………….. .
Answer:
easily

Question 2.
The structure of complex machine is ………….. .
Answer:
complicated

Question 3.
The more gradual the the ………….. lesser is the we bear. But, such an inclined plane is ………….. .
Answer:
slope, weight, longer

Question 4.
The steeper the ………….. , the ………….. is the inclined plane. But we have to bear a …………. weight.
Answer:
slope, shorter, greater

Question 5.
A screw is like a rolled up inclined plane made of an ………….. strip.
Answer:
iron

Question 6.
A wedge is used for ………… an object into two pieces or to ………….. the objects stuck together.
Answer:
breaking, separate

Question 7.
A farmer uses a strong …………. to remove the big stone bogged down in the farm.
Answer:
crow-bar

Question 8.
A device with a grooved wheel and thread designed to lift weights is called a …………. .
Answer:
pulley

Question 9.
When we use a pulley, force is applied in the downward direction for lifting the weight in an …………. direction.
Answer:
upward

Question 10.
Combination of an axle and a wheel is a …………. machine.
Answer:
simple

Question 11.
A needle and a nail are also kind of …………. .
Answer:
wedge

Question 12.
Machines are covered when not in use to prevent …………. settling on them.
Answer:
dust

Question 13.
In Archimedes’ screw, the pipe was placed at an angle of …………. with one end inside the …………. and the rod resting on a …………. .
Answer:
45°, water, flat surface.

Match the columns:

Question 1.

Answer:

Question 2.

Answer:

State whether the following statements are ‘true’ or ‘false’.

Question 1.
Lever helps big vehicle to climb up and down the mountain easily.
Answer:
False

Question 2.
Combination of wheel and axle is a simple machine.
Answer:
True

Question 3.
In pulley, force can be applied in upward direction.
Answer:
False

Question 4.
Screw is an example of wedge.
Answer:
False

Question 5.
In Archimedes screw, the rod rests on flat surface.
Answer:
True

Question 6.
A slanting plank is used to lift a weight.
Answer:
True

Question 7.
A winding road or ghat is an example of lever of first order.
Answer:
False

Answer the following questions in one sentence.

Question 1.
What is a machine?
Answer:
Devices which are used to get more work done in less time and less effort are called machines.

Question 2.
What is a simple machine?
Answer:
Machines which have only one or two parts and a simple and easy structure are called simple machines.

Question 3.
What is a complex machine?
Answer:
Some machines have many parts and they carry out many processes for completing a task. For this purpose, the parts are joined to each other. They are called complex machines.

Question 4.
List the properties of simple machines.
Answer:
Properties of simple machine are:

1. They are made up of only one or two parts.
2. They have a simple and easy structure.
3. They can be handled easily.
4. There are less chances of simple machines breaking down or getting damaged.

Question 5.
List properties of complex machines.
Answer:
Properties of complex machine are:

1. These machines have many parts to carry out many processes.
2. The parts are joined to one another.
3. The structure of complex machines is complicated.
4. Some parts of complex machines are actually simple machines.

Question 6.
What is an inclined plane?
Answer:
A slanting plank which is used to lift a weight on which we bear less weight and lifting becomes easier is an inclined plane.

Question 7.
What is a screw?
Answer:
A screw is like a rolled up inclined plane made up of iron strip.

Question 8.
What is a wedge?
Answer:
A wedge is used for breaking an object into two pieces or to separate objects stuck together.

Question 9.
State examples of wedges.
Answer:
An axle, a knife, a chisel, a needle and a nail are different kinds of wedges.

Question 10.
What is a lever?
Answer:
A lever is a machine made up of 3 parts: effort, load and fulcrum.

Question 11.
What is a fulcrum?
Answer:
The support at which the rod of a lever is rested is called fulcrum of a lever. The lever rotates about the fulcrum.

Question 12.
What is a load?
Answer:
The weight lifted by a lever or the force against which the lever acts is called a load.

Question 13.
What is a load arm?
Answer:
The arm of the lever from the fulcrum to the load is called a load arm.

Question 14.
What is an effort?
Answer:
The force applied on the other end of the rod to lift the load is called an effort.

Question 15.
What is an effort arm?
Answer:
The part of the lever from the fulcrum to the effort is called an effort arm.

Question 16.
What is lever of the first order?
Answer:
The fulcrum is in the centre, the load is at one end while effort is at other end.

Question 17.
What is lever of the second order?
Answer:
The load is in the centre, the fulcrum on one side, and the effort on the other side.

Question 18.
What is lever of the third order?
Answer:
The effort is in the centre, the fulcrum on one side, and the load on the other side.

Question 19.
What is a pulley?
Answer:
A pulley is a device with a grooved wheel and thread designed to lift weights.

Question 2.
How does a pulley help us?
Answer:
If we use a pulley, force can be applied in the downward direction for lifting the weight in an upward direction. It is convenient and easy.

Give scientific reasons:

Question 1.
We use many simple machines in our day-to-day life.
Answer:
Simple machines can be handled easily and there are less chances of these machines breaking down or getting damaged. Hence, we use many simple machines in our day-to-day life.

Question 2.
Less force is required to fit a screw than to hammer a nail.
Answer:

1. A screw is like a rolled-up inclined plane of an iron strip.
2. When a screw is fitted in wood it goes in as if it is going down an inclined plane.
3. Therefore, less force is required to fit a screw than hammer a nail.

Question 3.
Big vehicles easily climb up and down the mountains than a pathway.
Answer:
A winding road or ghat that goes up a mountain is like an inclined plane wrapped around the mountain. It helps big vehicles to climb, up and down the mountain easily.

Question 4.
Oil or lubricant is released between parts of machine.
Answer:
Oil or lubricant is released between parts that rub against each other so that there is less friction between them and wearing is reduced.

Question 5.
Machines are covered when not in use.
Answer:
Machines are covered when not in use to prevent dust settling on them.

Question 6.
How are machines protected from the effect of weather?
Answer:
To prevent the effect of weather, metallic parts in a machine are painted externally and the machines are always kept dry.

Draw the neat and labelled diagram of following:

Question 1.
The screw as an inclined plane.
Answer:

Question 2.
Archimedes’ screw
Answer:

Observe the following diagram and identify the order of lever.

Question 1.
Removing the lid.
Answer:

Question 2.
Picking up an object.
Answer:

Question 3.
Lifting a paper weight.

Answer:

1. Lever of the second order
2. lever of third order
3. Level of first order.

Answer each of the question in brief:

Question 1.
With the help of the diagram explain lever of the 1st, 2nd, 3rd order.
Answer:
1. Lever of the First order: The fulcrum is in the centre, the load is at one end, while the effort is at the other end. e.g. scissors

2. Lever of the Second order: The load is in the centre, the fulcrum on one side, and the effort on the other side. e.g. lid opener

3. Lever of the Third order: The effort is in the centre, the fulcrum on one side, and the load on the other side. e.g. Tongs

Question 2.
How can machines be maintained?
Answer:

1. To maintain machines, all its parts are wiped clean.
2. Oil or lubricant is released between parts that rub against each other.
3. Machines are covered, painted externally and always kept dry.

Question 3.
What is an inclined plane? Explain longer and shorter inclined plane.
Answer:

1. A slanting plank used to lift a weight, is called an inclined plane. Because of inclined plane we will experience less weight and weight lifting become easier.
2. Longer inclined plane: When the inclined plane is longer, the slope is more gradual and lesser is the weight we bear.
3. Shorter inclined plane: When the inclined plane is shorter, the slope is steeper and greater is the weight we bear.

Question 6.
Explain the working of a giant wheel.
Answer:

1. The giant wheel is fitted to a rod at its centre. This rod is called an axle.
2. When the axle starts rotating with the help of electricity the wheel fitted to it starts rotating.
3. This combination of an axle and a wheel is a simple machine.

Observe and discuss:

Question 1.
Name the devices and discuss how they help.

Answer:

1. Needle and thread – Stitching of clothes
2. Wheelbarrow – To carry materials.
3. Opener – To open the lids of bottles.
4. Pulley – To lift bucket
5. Nail cutter – To cut nails
6. Axe – To cut wood into small pieces

Can you tell?

Question 1.
Observe the machines shown in the following pictures. For what purposes are they used? Can you name some other machines of this kind?

Answer:

1. Mixer grinder – To grind the foodstuffs
2. Scooter – To ride and reach places
3. Bicycle – To ride and reach places
4. Sewing machine – To stitch clothes
5. Wheel chair – Specially designed for handicapped patients to move around.

Question 2.
Compare the pathway and a road, available to climb the mountain, the time and strength and your convenience, required to reach the mountain top.
Answer:
We can reach the mountain top by climbing the pathway early than by the road. The time required is less but the strength required is more. The road is easy to walk and more time consuming.

Question 3.
If the point of a needle or the edge of a knife become blunt, then the needle does not penetrate the cloth and the knife does not cut into the fruit. Why is this so?
Answer:
The tip of the needle or the edge of a knife becomes blunt due to regular use. Both the knife and the needle lose their sharpness.

Use your brain power!

Question 1.
Which task can be done using a lever?
Answer:
Task such as using a nut cracker, cutting paper with scissors, can be done using a lever.

Question 2.
Some machines we use in our day to day life are shown in picture. What is the type in each of these?

Answer:

• Wheelbarrow – Lever of the third order
• Pair of tongs – Lever of the first order
• See – saw – Lever of the first
• order Cutter – Lever of the second lever
• Pair of Scissors – Lever of the first order.

Question 3.
When the pedal of the bicycle is rotating, the wheel starts rotating. How does this happen?
Answer:
Pedals of the bicycle are connected to the wheels through the axle, when the axle starts rotating, the wheels also start rotating.

Question 4.
Examples of pulley.
Answer:

1. A simple pulley is used to hoist a flag, to draw water from a well.
2. The crane which is used to lift heavy loads is an example of application of pulleys and levers working together.

Maharashtra State Board Class 6 Science Solutions Chapter 13 Sound

Class 6 Science Chapter 13 Sound Textbook Questions and Answers

1. Fill in the blanks with the proper words.

Question a.
The propagation of sound does not occur through a ………….. .
Answer:
vacuum

Question b.
Noise pollution is a …………… issue.
Answer:
social/serious

Question c.
The sound which is disagreeable to our ears is called …………… .
Answer:
noise

Question d.
Noise has adverse effects on our …………….. .
Answer:
health

2. What should we do?

Question a.
The silencer of a motorcycle is broken.
Answer:

1. If the silencer of a motorcycle is broken, vehicle should be immediately taken to the garage for repair.
2. If silencer is not maintained properly, it will continue making loud noise on the road while in motion, resulting in increasing noise pollution.

Question b.
A factory in the surrounding is producing continuous loud noise.
Answer:
Factories should be located at a proper distance away from residential areas. Authorities should be contacted who will control the decibel level.

3. Write the answers in your own words.

Question a.
What is meant by vibration?
Answer:
Vibration of an object is necessary for the production of sound. As long as the object vibrates, the sound is heard. When the vibration stops, the sound also stops.

Question b.
Explain with the help of practical examples how sound is propagated through solids.

Answer:

1. Singing
2. Chirping of birds
3. Bursting of crackers
4. Whispering
5. Whistling
6. Flute
7. Honking
8. Dog barking

Question c.
What is meant by noise pollution?
Answer:
Continuous noise which has ill effects is called noise pollution.

Question d.
What measures will you take to control noise pollution?
Answer:
Measures for preventing noise pollution:

1. As far as possible, we should avoid blowing horns.
2. The volume of the TV or radio in the house should be restricted to those watching the programmes.
3. Vehicles should be maintained properly to reduce the unnecessary sounds they produce.
4. Factories, airports, railway stations and bus stands should be located at the proper distance away from residential area.
5. Planting of trees helps reduce noise as trees act as a natural barrier.

4. Complete the table.

Question a.

Answer:

Project:

Question 1.
Prepare a list of the harsh sounds mheard near your house. Write about those sounds which produce noise pollution.

Question 2.
Collect information about places where loud noise is prohibited and discuss why it is so.

Class 6 Science Chapter 13 Sound Important Questions and Answers

Fill in the blanks:

Question 1.
Some sounds are ……………… and are heard easily.
Answer:
loud

Question 2.
Some sounds are very ……………… and cannot be heard unless we listen attentively.
Answer:
soft

Question 3.
As long as the object ……………… the sound is heard.
Answer:
vibrates

Question 4.
When the vibration ……………… the sound also stops.
Answer:
stops

Question 5.
The intensity of sound is measured in a unit called ……………… .
Answer:
decibels(dB)

Question 6.
The voice box is located in our ……………… .
Answer:
throat

Question 7.
Sound travels in the form of ……………… through air, water and ……………. .
Answer:
waves, solids

Question 8.
The sound is propagated more clearly through a ……………… than through air.
Answer:
solid

Question 9.
Transmission of sound occurs at a different ……………… through different mediums.
Answer:
speed

Question 10.
Continuous noise which may have ill effects, is called noise ……………… .
Answer:
pollution

Question 11.
Some of the sounds that we enjoy can be a ……………… for others.
Answer:
nuisance

Question 12.
The vibration of an object is necessary for the ……………… of sound.
Answer:
production

Answer in one sentence.

Question 1.
List characteristics of sound.
Answer:
Sounds are soft, loud, pleasant and unpleasant.

Question 2.
What do you mean by unpleasant sounds?
Answer:
The sounds by which we get annoyed are called unpleasant sounds.

Question 3.
What do you mean by loud and soft sounds?
Answer:
The sounds which are heard easily, are loud sounds and the sounds which cannot be heard unless we listen attentively, are soft sounds.

Question 4.
Which movement is exhibited by diaphragm of a speaker and a tabla?
Answer:
Diaphragm of a speaker and a tabla exhibit rapid oscillatory motion which gives rise to vibrations.

Question 6.
What is source of the sound?
Answer:
The object due to which sound is produced is called the source of the sound.

Question 7.
What is acoustics?
Answer:
The science of sound, resonance, production, propagation and effects of sound is called acoustics.

Question 8.
What produces sound in living beings?
Answer:
The vibration of the vocal chords in our larynx or voice box produces sound.

Question 9.
On what does quality of sound depend?
Answer:
Quality of sound produced in the larynx depends upon the tautness of the vocal chords.

Question 10.
How is sound propagated?
Answer:
The sound is propagated in the form of waves through air, water or through a solid.

Question 11.
Why is sound heard more clearly through solids?
Answer:
Transmission of sound occurs at a different speed through different mediums. Transmission of sound is faster through a solid than through a liquid and gas.

Question 12.
What is noise?
Answer:
A loud sound is harsh to ears. Such sounds produce noise.

Question 13.
List the effects of very loud or continuous noise on the people.
Answer:

1. Very loud or continuous noise can cause hearing impairment.
2. This can even lead to deafness.
3. It also causes restlessness, irritability and mental exhaustion.

Question 14.
What is noise pollution?
Answer:
Continuous noise which has ill effects is called noise pollution.

Question 15.
How can we prevent noise pollution with respect to watching TV?
Answer:
The volume of the TV or radio in the house should be restricted to those watching the programmes.

Explain the terms.

Question 1.
Propagation of sound:
Answer:
Sound is said to be propagated when sound waves spread in all directions from a source of sound.

Question 2.
Medium of propagation of sound:
Answer:
The substance around a source of sound through which sound waves spread is called the medium of propagation of sound.

Question 3.
Which sounds do you hear during the recess in the school?
Answer:
During the recess in the school, we hear.

1. laughing
2. students running
3. talking loudly
4. ringing of the bell
5. stamping on the staircase
6. shouting

Question 4.
When there is silence in the classroom, close your eyes and sit quietly. Which sounds in your surroundings can you hear now?
Answer:

1. Loud: Laughing, running, talking, horn of cars, marriage procession, school band, teacher’s voice in next classroom.
2. Pleasant: P.T. teacher’s whistle, chirping of birds.
3. Unpleasant: Shouting, bell ringing, stamping on staircase, dog barking, horns of vehicles.

Question 5.
When a song is being played on a radio or a music system in the house, place your hand on its speaker. What do you feel? Put off the music. What do you feel now?
Answer:

1. When a hand is placed on the speakers of the music system, we feel vibrations on the hand.
2. When music is put off, we don’t feel any vibrations on the hand.

Question 6.
When a metal dish falls on the floor; it makes a loud noise. What do we do to stop the noise? What is the effect of that action?
Answer:
To stop the noise of metal dish falling on the floor, quickly put hand on the dish. Vibrations of the metal dish are stopped and the noise stops.

Question 7.
What is it that vibrates when the sounds of sitar, bell, water tap, and breaking of a saucer, etc. are produced?
Answer:
Strings of the sitar, tongs of the bell, water drops hitting the floor of the basin, pieces of saucers that hit the ground vibrate to produce the sounds.

Question 8.
Take a pot full of water. Strike it lightly on the rim. What do you see? Why are waves formed on the water in the pot?
Answer:

1. We see ripples on the water.
2. When we strike the rim of the pot, our striking causes vibrations. These vibrations are transferred or moved from the pot to the water. Hence, water waves/ripples are seen on the water in the pot.

Question 9.
On rubbing balloon filled with water and another filled with air, of which balloon do we hear a clear or sound?
Answer:
We hear a clearer sound of the water balloon.

Question 10.
If a bell is rung in a vacuum container, will its sound be heard outside?
Answer:
Its sound will not be heard outside.

Observe and Discuss.

Observe the figure and answer the questions.

Question 1.
Which of these sounds is pleasant?
Answer:
The singing of the girl is a pleasant sound.

Question 2.
Which sound is a nuisance to people?
Answer:

1. Boy shouting/screaming.
2. Boy moving/ walking with a toy rattle.

Observe the figure and answer the following.

Question 1.
Make a list of all sounds implied in the picture.

Answer:

1. Chirping of bird outside the house on the tree.
2. Collision of two vehicles – honking of the vehicles.
3. Baby crying.
4. Father talking on the phone.
5. Brother playing in the house – jumping.
6. Sister playing the drum – hitting the drum.
7. Sound of TV.
8. Dog barking.
9. Mother talking to the neighbour.

Question 2.
How would this atmosphere affect a person who is not feeling well?
Answer:
This atmosphere is not convenient for a patient who is ill. He cannot take rest.

Question 3.
Would you be able to study in these conditions?
Answer:
No, students cannot study in this condition. They cannot concentrate on their study.

Maharashtra State Board Class 6 Science Solutions Chapter 7 Nutrition and Diet

Class 6 Science Chapter 7 Nutrition and Diet Textbook Questions and Answers

1. Fill in the blanks:

Question a.
The process of intake of food and utilizing it for all life processes is called ……………. .
Answer:
nutrition

Question b.
All the substances in our food which are useful for various body processes are called ………… .
Answer:
nutrients

Question c.
Carbohydrates and …………. provide …………… to our body.
Answer:
fats, energy

Question d.
In a balanced diet, all the nutrients are present in the ……………. proportion.
Answer:
right

Question e.
In the food pyramid, cereals are given the maximum space because they fulfill our …………… requirement.
Answer:
energy

Question f.
Intake of more food than necessary causes ………….. .
Answer:
overnutrition

2. Spot the following in the table of vitamins and minerals.

Question a.
The nutrient present in citrous fruits.
Answer:
Vitamin C

Question b.
Vitamins/minerals present in milk.
Answer:
Vitamin A, Vitamin B, Vitamin D, calcium, phosphorus.

Question c.
Causes and symptoms of night blindness, scurvy, rickets, beriberi.
Answer:

Question d.
Foods required to prevent the above diseases.
Answer:

Question e.
Causes of anaemia.
Answer:
Deficiency of Vitamin B₁₂, iron.

Question f.
Essential mineral for healthy bones and teeth.
Answer:
Calcium, phosphorus.

Question g.
Sensory organ affected due to the deficiency of Vitamin A.
Answer:
Eyes, skin.

3. Choose the correct alternative. 

Question a.
Pulses are a very good source of ……………. .
(1) carbohydrates
(2) proteins
(3) fats
(4) minerals
Answer:
(2) proteins

Question b.
…………. provide maximum energy to our body.
(1) Cereals
(2) Leafy Vegetables
(3) Water
(4) Amla
Answer:
(1) Cereals

Question c.
Goitre is caused by the deficiency of ……….. .
(1) iron
(2) calcium
(3) iodine
(4) potassium
Answer:
(3) iodine

Question d.
……….. is a type of junk food.
(1) Orange
(2) Milk
(3) Bhakri
(4) Chocolate
Answer:
(4) Chocolate

4. Use the food pyramid to select food items of your choice for three days.
Conditions:
1. The diet for all three days should be balanced.
2. There should be variety in the items chosen for the three days.
Answer:

Day 1:
Cereal like cornflakes and milk, apple, roti, sabzi and dal.

Day 2:
Bread and butter with milk, rice/ roti and chicken, curd, any one type of fruit, salad.

Day 3:
Poha, green vegetable and dal with rice or roti, raita, one fruit, vegetable sandwich.

Activity:

Question 1.
Obtain information on simple methods of spotting the adulteration in foodstuffs and try them out.

Class 6 Science Chapter 7 Nutrition and Diet Important Questions and Answers

Choose the correct alternative:

Question 1.
Vitamin ……………. and vitamin …………….. dissolve easily in water.
(a) A, B
(b) B, C
(c) B, D
(d) B, E
Answer:
(b) B, C

Question 2.
……………. carries oxygen to all parts of the body.
(a) Calcium
(b) Iron
(c) Iodine
(d) Sodium?
Answer:
(b) Iron

Question 3.
Deficiency of vitamin ……………. causes excessive bleeding after an injury.
(a) A
(b) B
(c) K
(d) D
Answer:
(c) K

Question 4.
In accordance with the food pyramid, the proportion of ……………. should be least in our diet.
(a) cereals
(b) fruits
(c) milk
(d) oil
Answer:
(d) oil

Question 5.
……………. is a rich source of vitamin C.
(a) Carrot
(b) Amla
(c) Meat
(d) Milk
Answer:
(b) Amla

Question 6.
Children of growing age need to get approximately ……………. to ……………. calories from the food they eat.
(a) 1500-2000
(b) 3150-4150
(c) 2000-2500
(d) All of them
Answer:
(c) 2000-2500

Fill in the blanks:

Question 1.
All food that we consume during the day is together called our ………. .
Answer:
diet

Question 2.
………….. convert milk into yogurt.
Answer:
Probiotics.

Match the columns:

Question 1.

Answer:

Question 2.

Answer:

Question 3.

Answer:

Pick out the odd one:

Question 1.
Chocolate, chapatti, banana, milk
Answer:
Chocolate

Question 2.
Rice, chapatti, carrot, dal.
Answer:
Carrot

Question 3.
Scurvy, Rickets, Beriberi, Goitre.
Answer:
Goitre

Question 4.
Vitamin A, Vitamin C, Vitamin D, Vitamin E
Answer:
Vitamin C

Answer the following:

Question 1.
Why do living things need food and water?
Answer:
Living things take food and water and use them for:

1. Obtaining energy
2. Growth of the body
3. Carrying out day to day functions of the body.
4. Fighting against diseases

Question 2.
Name the main nutrients in our food.
Answer:
There are six main nutrients in our food. They are:

1. Carbohydrates
2. Fats
3. Proteins
4. Fibres
5. Vitamins
6. minerals

Question 3.
How do we get energy from the food?
Answer:

1. We get energy in the form of heat from the food we eat.
2. Heat is measured in kilocalories (calories).
3. Hence, the energy in food items is also measured in kilocalories (calories).

Question 4.
Vitamin C rich food should be eaten raw. Why?
Answer:

1. Vitamin C is very sensitive to heat and light.
2. It is destroyed easily during cooking. Hence, Vitamin C rich food should be eaten raw.

Question 5.
What is balanced diet? Give its significance.
Answer:
A diet containing adequate quantities of all nutrients is called as balanced diet. Significance of a balanced diet are:

1. An increased capacity to work.
2. Good physical and mental health.
3. Increased capacity to fight/resist diseases.
4. Helps in proper growth of the body.

Question 6.
What is obesity? How to avoid obesity?
Answer:

• Obesity is the state of being overweight.
• Junk food eaten frequently causes obesity.
• Obesity is not good for health.

To avoid obesity:

1. Have a balanced diet.
2. Eat whole grains, fruits and vegetables with their skins.
3. Increase use of bicycles.
4. Play more outdoor games.
5. Do not eat if you are not hungry.
6. Do not watch T.V while eating.
7. Avoid precooked, packaged food.
8. Exercise regularly.

Write short notes.

Question 1.
Vitamins:
Answer:
1. Vitamins are vital substances required by our body in small quantities. They help to improve the body’s resistance to diseases. Their deficiency can lead to various diseases, e.g.: deficiency of Vitamin A causes night blindness and that of Vitamin D causes rickets. The sources of vitamins are vegetables, fruits, milk, fish, meat etc.
2. There are two kinds of vitamins – water soluble vitamins and water insoluble vitamins.
3. Vitamin B and Vitamin C are water soluble vitamins because they dissolve easily in water. They are thrown out of the body through the water in sweat and urine. Hence, a regular supply of these vitamins is essential. B₁₇B₂, B₃, B₆, B₉, and Bp are the types of vitamin B.
4. Vitamins A, D, E and K are insoluble in water but are fat soluble vitamins. They get stored in the body.

Question 2.
Probiotics:
Answer:

1. The useful microorganisms which convert milk into yoghurt are present in yoghurt and buttermilk are called probiotics.
2. Lakhs of such useful microorganisms are present in our intestine.
3. They are essential for our health.
4. Hence, to maintain them in our body we should include food rich in probiotics in our daily diet.

Question 3.
Junk food:
Answer:

1. Foods which gives us energy but do not supply the necessary nutrients are called junk food.
2. Foods like chocolate, pizzas, burgers, noodles, fried foods like pakodas are junk food.
3. These foods contain refined flour, sugar and oil in large proportion.
4. If we consume these foods frequently, our body experiences shortage of proteins, vitamins and minerals.
5. This may lead to malnutrition and obesity.

Question 4.
Adulteration of food:
Answer:
To earn more profits, cheaper substances of low quality called adulterants, are mixed with the foodstuffs. The mixing adulterants to foodstuffs is called adulteration of food. Adulterants may be poisonous or harmful and such food is impure and unfit for consumption.
Some of the adulterants added to foodstuffs are given below:

Give scientific reasons:

Question 1.
Deficiency of vitamin B and C are common in our body.
Answer:

1. Vitamin B and vitamin C are water soluble vitamins.
2. They are thrown out of the body through the water in sweat and urine.
3. Hence, a regular supply of these vitamins is essential.
4. If we don’t intake food rich in these vitamins, deficiency occurs.

Question 2.
Exposure to sunlight is essential.
Answer:

1. On exposure to sunlight our body synthesizes Vitamin D from substances in milk, fish, eggs and butter.
2. Its deficiency causes softening of bones (Rickets).
3. Vitamin D helps in absorbing calcium and phosphorous for healthy bones and teeth.
4. Hence, exposure to sunlight is essential.

Complete the tables given below:

1.

2.

3.

Using the food items given below, prepare a balanced diet pyramid.
[Chapatti, banana, carrot, butter, Nan, egg, bread, cheese, dal, spinach, milk]
Answer:

Can you recall?

Question 1.
Which are the various groups of foodstuff? Which main constituents of food do we get?
Answer :
The various groups of foodstuffs are:

1. Milk and milk products, meat, fish, eggs.
2. Cereals and pulses
3. Vegetables and fruits.
4. Fatty substances oil, butter and ghee.

There are six main nutrients in our food: carbohydrates, fats, proteins, fibres, vitamins and minerals.

Question 2.
What trouble do we have to face if we do not get enough fibre from our daily diet?
Answer:
Fibres help in excretion of food, if we do not get enough fibre we will face indigestion and stomach-ache.

Question 3.
What care must be taken to make sure that fibre is not lost or removed from the food we get?
Answer:
We must not over-cook the foodstuff containing fibres. Fruits should be eaten raw.