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Natural Resources - class 9 science Textbook solutions

 Natural Resources

1.How is our atmosphere different from the atmospheres on Venus and Mars?

Both Venus and Mars have 95.97% of the carbon dioxide. But in our earth 0.02% of carbon dioxide is present. Our earth has 21% of oxygen which is necessary for all living beings. In this way, Earth’s atmosphere is different from the atmosphere on Venus and Mars.

2.How does the atmosphere act as a blanket?

Atmosphere is covering the earth, like a blanket, we know that air is a bad conductor of heat. The atmosphere keeps the average temperature of the earth fairly steady during the day and even during the course of the whole year. The atmosphere prevents the sudden increase in temperature during the daylight hours. And during the night, it slows down the escape of heat into outer space.

3.What causes winds?

In the coastal regions, during the day, the air above the land gets heated and starts rising. As this air rises, a region of low pressure is created and air over the sea moves into this area of low pressure. The movement of air from one region to the other creates winds,

4.How are clouds formed?

When water bodies are heated during the day, a large amount of water evaporates and goes into the air-some amount of water vapour also get into the atmosphere because of various biological activities. This air also gets heated. The hot air rises up carrying the water vapour with it. As the air rises, it expands and cools. The cooling causes the water vapour in the air to condense in the form of tiny droplets. This condensation of water is facilitated if some particles could act as the nucleus for these drops to form around. Normally dust and other suspended particles in the air perform this function.

5.List any three human activities that you think would lead to air pollution.

Following are the three human activities which leads to air pollution.
1.    Burning of fossil fuels leads to air pollution.
2.    By the destruction of forests.
3.    By industrialisation.

6.Why do organisms need water?

All cellular processes take place in a water medium. All the reactions that take place in a water medium. All the reactions that take place within our body and within the cells occur between substances that are dissolved in water.
Substances are also transported from one part of the body to the other in a dissolved form. Hence organisms need to maintain the level of water within their bodies in order to stay alive. Hence organisms need water.

7.What is the major source of freshwater in the city/town/village where you live?

In some places, the river is the major source of fresh water. In some places, freshwater is available from borewells. Tungabhadra river is the major source for us. (Gadag district)

8.Do you know of any activity which may be polluting this water source? ‘

1.    The addition of undesirable substances to water bodies. These substances could be the fertilizers and pesticides used in farming or they could be poisonous substances like mercury salts which are used by paper industries.
2.    Releasing drainage water and effluents from industries to nearby water resources.
3.    Releasing superheated water to rivers.
4.    Change in temperature of river water.
These are the activity from which water gets polluted.

9.How is soil formed?

Over long periods of time thousands and millions of years, the rocks at or near the surface of the Earth are broken down by various physical, chemical, and some biological processes. The end product of this breaking down is the fine particles of soil. The Sun, water, and wind are also factors helpful for the formation of soil.

10.What is soil erosion?

Flowing water and blowing wind carries soil particles along with them. This is called soil erosion.

11.What are’ the methods of preventing or reducing soil erosion?

1.    The roots of plants have an important role in preventing soil erosion.
2.    We should give importance to reforestation. Afforestation programmes instead of deforestation.
3.    Vegetative cover on the ground has a role to play in the percolation water into the deeper layers too. In the hilly or mountainous region, we should grow more grass.
By these methods, we can prevent or reduce soil erosion.

12.What are the different states in which water is found ‘during the water cycle?

Water is found in solid, liquid, and gaseous states during the water cycle.

13.Name two biologically important compounds that contain both oxygen and nitrogen.

1.    Oxygen:
o    Carbon dioxide
o    Phosphorus pentoxide.
2.    Nitrogen:
o    Amino acid
o    Protein.

14.List any three human activities which would lead to an increase in the carbon dioxide content of air.

1.    Breathing
2.    Burning of fuels
3.    Overuse of vehicles.

15.What are the greenhouse effects?

Some gases prevent the escape of heat from the earth. An increase in the percentage of such gases in the atmosphere would cause the average temperatures to increase worldwide and this is called the greenhouse effect.

16.What are the two forms of oxygen found in the atmosphere?

Carbon dioxide and water vapour are the two forms of oxygen found in the atmosphere.

1.Why is the atmosphere essential for life?

(a) to establish all forms of life.
(b) necessary vital components can be – recycled.
(c) maintenance of temperature.
(d) a suitable environment for all forms of life.
(e) ozone a protective layer.

2.Why is water essential for life?

All organisms require water for their survival. All cellular processes take place in a water medium. All the reactions that take place within our body and within the cells occur between substances that are dissolved in water. Substances are also transported from one part of the body to the other in a dissolved form. In this way water is essential to us.

3.How are living organisms dependent on the soil? Are organisms that live in water totally independent of soil as a resource?

Soil supplies various nutrients which are essential for all organisms. Even soil is necessary for the fixing of plants firmly and increases the level of underground water. Even organisms that live in water are also totally dependent of soil as a resource. They are not surviving without soil.

4.You have seen weather reports on television and in newspapers. How do you think we are able to predict the weather?

Because of scientific equipment, we come to know about the weather reports. For example, if there is a depression in a barometer, we may expect heavy rainfall. By such phenomena, we are able to predict the weather.

5.We know that many human activities lead to increasing levels of pollution of the air, water-bodies, and soil. Do you think that isolating these activities to specific and limited areas would help in reducing pollution?

1.    Farmers should use pesticides and insecticides judiciously so that no soil pollution takes place.
2.    We should not allow effluents (wastes from industries) to mix with river water. Superheated water should not mix with river water.
3.    We can prevent air pollution by tree plantation programmes.
All these are the preventive measures to avoid soil, water, and air pollution.

6.Write a note on how forests influence the quality of our air, soil, and water resources.

Forests are useful to us in many ways. They are as follows:
1.    Plants take carbon dioxide which we give out during respiration and we get oxygen from plants which are very essential to us.
2.    Plants increase water content in the underground. Roots of the plants minimize soil erosion and there is an increase in the water holding capacity.
3.    Because of the number of trees, no soil erosion takes place. Roots bind soil particles and more water is stored.

Additional Questions and Answers

Fill in the blanks with suitable words:

1.Nearly _________ % of earth’s surface is covered with water.

75 %.

2.Air _______ and ______ as it goes up.

expands, cools

3.When the temperature of the air is low enough, precipitation may occur in the form of _____, ______ or _____

snow, sleet, hail.

4.If we intake polluted air continuously, we have to suffer from diseases like ______ and ______

Allergy, cancer and heart disease.

5.The outer covering of the earth is called ______


Answer the following questions:

1.What is the importance of Humans?
Answer :

It is a major factor in deciding the soil structure because it causes the soil to become more porous and allows water and air to penetrate deep underground.

2.Write the importance of topsoil?
Answer :

The topmost layer of the soil that contains humus and living organisms in addition to the soil particles is called topsoil, it is important to factor that decides biodiversity in that area.

3.Mention the two important components of biogeochemical cycles.
Answer :

•    Reservoir pool
•    Exchange pool

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