NCERT Solutions for Class 9 Science Chapter 14 Natural Resources

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NCERT Solutions for Class 9 Science Chapter 14 Natural Resources help the students to understand the concepts in a better way and prepare them for their exams. The solutions are also very detailed, giving students a better understanding of the concepts.

Chapter 14 CBSE Class 9 Science NCERT Solutions are created by expert teachers who have years of experience in teaching the subject matter. These are very much essential in steering students towards their goal.

Chapter 14 Natural Resources Class 9 Science NCERT Solutions

In Text Questions

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

Solution

Our atmosphere consists of nitrogen, oxygen, carbon dioxide, water vapours etc which help in the existence of life. But the atmosphere on Venus and Mars is largely consist of carbon dioxide (95% to 97%).

2. How does atmosphere act as a blanket?

Solution

Atmosphere acts as a blanket because of the following reasons:
(i) Air is a bad conductor of heat.
(ii) It keeps the average temperature of the Earth fairly steady during the day and even during the course of whole year.
(iii) It prevents sudden increase or decrease in the temperature.

3. What causes winds?

Solution

An uneven heating of the Earth’s surface causes winds. Air becomes lighter and rises up on being heated. As a result, a region of low pressure is created. Then, air from a high pressure region moves to a low pressure region. This is the reason of winds.

4. How are clouds formed?

Solution

Clouds are formed by the condensation of water droplets in the air. Large amount of water evaporates and goes into the air. As air rises up, it expands and cools. This cooling of air causes water vapour present in the air to condense and form tiny droplets of water. These water droplets get bigger and form clouds.

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

Solution

(i) Combustion of fossil fuels
(ii) Industrialisation
(iii) Deforestation

6. Why do organisms need water?

Solution

The organisms need water:
(i) For different cellular process.
(ii) For transportation of substance from one place to another inside the body.
(iii) Substances are transported from one part of the body to the other in a dissolved form, which requires water.
(iv) Water helps in maintaining the temperature of the body.

2. What is the major source of fresh water in the city/town/village where you live?

Solution

The major sources of fresh water are underground water, surface water like rivers, lakes, ponds, stored rain water, etc.

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

Solution

The discharge of waste water from homes, industries, hospitals, excessive use of fertilizers etc. into the river pollutes this fresh water source.

1. How is soil formed?

Solution

The breaking up of rocks at or near the surface of Earth over long periods of time results in soil formation. The rocks are broken down by various physical, chemical and biological processes. The end products of this breaking down are the fine particles of soil.
(i) Sun: The rocks are heated up by solar rays during day. Due to this heat rocks expand. These rocks
cool down and contracts during night time and due to this process the rocks break down.
(ii) Water breaks rocks both by freezing and by its fast flow.
(iii) Wind : Strong winds carry away rocks, which causes rubbing of rocks. This results in the
breaking down of rocks into smaller and smaller particles.
(iv) Living Organism : Some living organisms like lichens help in the formation of soil.

2. What is soil erosion?

Solution

Removal of the top fertile layer and useful components of the soil, which adversely affects the fertility of the soil is called soil erosion.

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

Solution

(i) Soil erosion can be prevented by planting trees and sowing grasses.
(ii) It can be prevented by intensive cropping.
(iii) It can be prevented by constructing strong embankments along river banks.
(iv) Soil erosion in hilly areas can be prevented by practising terrace farming.

1. What are different states in which water is found during water cycle?

Solution

Water is found in all three states, gaseous, liquid and solid during the water cycle in the form of ground water, surface water, water vapour, water droplets, clouds, etc.

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

Solution

Proteins and nucleic acids (DNA and RNA)

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

Solution

(i) Burning fossil fuels
(ii) Respiration
(iii) Deforestation

4. What is greenhouse effect?

Solution

The increase in global temperature due to a rise in CO2 levels is called greenhouse effect. It causes global warming.

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

Solution

The two forms of oxygen found in the atmosphere are diatomic form as oxygen (O2) and triatomic form ozone (O3).

Exercises

1. Why is the atmosphere essential for life?

Solution

(i) The atmosphere acts as a blanket and keeps the average temperature of the Earth steady during day and night and even during the course of the year.
(ii) Oxygen present in the atmosphere is essential for respiration and combustion; whereas carbon dioxide is essential for photosynthesis.
(iii) Rain and rainfall patterns are decided by the atmosphere.
(iv) Ozone layer present in the atmosphere absorbs ultraviolet rays and thus, protects living organisms from their harmful effects.

2. Why is water essential for life?

Solution

Water is essential for life because of the following reasons:
(i) Substances are dissolved in water during biological reactions.
(ii) Cellular processes need water as a medium to take place.
(iii) Transportation of biological substances needs water as a medium.

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

Solution

(i) Almost all living organisms are directly or indirectly dependent on soil.
(ii) Plants need nutrients from soil to prepare their food and other organism depend on plants for their food.
(iii) Organisms that live in water depend on aquatic plants for food and other substances. These aquatic plants require minerals for their sustenance. These minerals are carried to water bodies from soil by rivers, rain water, etc. Without the supply of mineral, it is impossible to imagine aquatic life.
(iv) Soil also supports the growth of crops, grasslands and forests, which provide us food, fibre, wood and building materials.

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

Solution

Weather can be predicted through:
(i) Movement of air which is due to the uneven heating of the atmosphere in different regions of the Earth
(ii) Rainfall patterns, which are decided by the prevailing wind pattern
(iii) Relative humidity
(iv) Pattern of cloud formation

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

Solution

Yes. Isolating human activities in particular areas would help in reducing levels of pollution. For example, Setting up of industries in isolated regions will not contaminate water resources, agriculture land, fertile land, etc. It will control pollution to some extent.

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

Solution

Forests are the lungs of the Earth. The plants in the forests take in CO2 for photosynthesis and release O2. Thus, they not only reduce air pollution but also help in maintaining a balance between O2 and CO2 in the atmosphere. It prevent soil erosion as roots of plants bind the soil tightly. It replenishment of water resources during the process of transpiration. Forests help in recharging water bodies and play an important role in maintaining the water cycle.

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