NCERT Solutions Class 9 Science Chapter 14 Natural Resources

NCERT Solutions Class 9 Science 

The NCERT Solutions in English Language for Class 9 Science Chapter – 14 (Natural Resources) has been provided here to help the students in solving the questions from this exercise. 

Chapter – 14 (Natural Resources) 

Questions

1. How is our atmosphere different from the atmospheres on Venus and Mars?
Answer – Our atmosphere contains gases like nitrogen, oxygen, carbon dioxide, water vapour and other gases in very small amount. Atmosphere of Venus and Mars have about 95% of carbon dioxide. So life is not possible.

2. How does the atmosphere act as a blanket?
Answer – The atmosphere acts as a blanket in the following ways:

• It keeps the average temperature of the Earth fairly constant during day time and even during the course of whole year.
• It prevents a sudden increase in the temperature during day time.
• It slows down the escape of heat from the surface of the Earth into outer space during night time.

3. What causes winds?
Answer – An uneven heating of the Earth’s surface causes winds. On being heated, air becomes lighter and rises up. As a result, a region of low pressure is created. Then, air from a high pressure region moves to a low pressure region, causing wind.

4. How are clouds formed?
Answer – The water evaporates due to heating up Of water bodies and other biological activities. The air also heats and rises. On rising, it expands and cools to form tiny droplets. These droplets grow bigger, expand and form clouds. The collection of dust and other suspended particles facilitate the process.

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

• Burning of fuels like coal, petroleum, kerosene.
• Smoke released from industries
• Emissions from vehicles.

Questions

1. Why do organisms need water?
Answer – Organisms need water for the following activities:

• All cellular processes occur due to water.
• Transportation of substances in our body takes place by dissolving in water.
• Terrestrial animals require fresh water for transportation of minerals and for getting rid of waste from their body.
• Plants require water for photosynthesis.

2. What is the major source of fresh water in the city/town/village where you live?
Answer – The major sources of water are:

• Water in the form of snow, ice-covered mountains.
• Underground water well.
• Surface water like in lakes, rivers, ponds.
• Rainfall.
• Stored rain water in tanks, dams.

3. Do you know of any activity which may be polluting this water source?
Answer – Yes, the water is polluted by

• Dumping waste in the river
• Factory waste
• Sewage

Questions

1. What are the different states in which water is found during the water cycle?
Answer – Water is found in all three states, like

• A solid-state (Snow, ice)
• Liquid state (river water, underground water)
• Gaseous state (water vapour)

2. Name two biologically important compounds that contain both oxygen and nitrogen.
Answer – Two biologically important compounds that contain both oxygen and nitrogen are:

• Amino acids
• Deoxyribonucleic acid (DNA) and Ribonucleic acid (RNA)

3. List any three human activities which would lead to an increase in the carbon dioxide content of the air.
Answer – Three human activities which would lead to an increase in the CO₂ (carbon dioxide) content of air are :

• Breathing process where carbon dioxide is released.
• Burning of petrol, coal, and fuel.
• Using fridge, air conditioners and oven.

4. What is the greenhouse effect?
Answer – Gases like carbon dioxide and methane trap the sun’s radiation and do not allow it to go back. This causes the warming of the atmosphere, resulting in the greenhouse effect.

5. What are the two forms of oxygen found in the atmosphere?
Answer – Oxygen is present in two forms, and they are

• Diatomic molecular form (O₂)
• Triatomic molecular form (O₃)

Exercise

1. Why is the atmosphere essential for life?
Answer – Atmosphere is very important for sustaining life:

• It contains various gases like O₂, CO₂, N2 which are required for various life processes by plants and animals.
• CO₂ gas is used by plants to prepare food by the process called photos.
• Oxygen is required for burning, combustion and respiration.
• Ozone layer is acting as a protective layer, which avoids/prevents U.V rays to enter the earth’s atmosphere..
• CO₂ dissolved in water forms carbonates which is required by animals to form shells.

2. Why is water essential for life?
Answer – Water is considered essential for life because of the following reasons :

• All cellular processes take place in 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.
• Water makes up about 70% of body weight of all living organisms.
• It helps in the digestion of food and absorption Of nutrients in the blood. Hence, organisms need to maintain the level of water within their bodies in order to stay alive.
• It helps in maintaining body temperature.

3. How are living organisms dependent on the soil? Are organisms that live in water totally independent of soil as a resource?
Answer – Living organisms are dependent on the soil in the following ways :

All living organisms are directly or indirectly dependent on soil. Plants obtain water, minerals from the soil and prepare food for animals. Other organisms that live in water are not totally independent of soil because the microbes growing on the soil in water are the primary producers which start the food chain and even other microbes that live in soil help in the decomposition of dead plants and animals in water to return the nutrients back to the water.  

4. You have seen weather reports on television and in newspapers. How do you think we are able to predict the weather?
Answer – Historical data on weather is stored in computers. These help in creating a model for weather pattern. Based on temperature humidity and wind speed of a given time frame; these data help meteorologists forecast 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?
Answer – Human activities are the main reason for the pollution of the air. Air is the medium to spread pollutants into various sources like water and soil. Hence, we can say that limiting activities in certain places will definitely help air pollution to be controlled to some extent.

6. Write a note on how forests influence the quality of our air, soil and water resources.
Answer – Role of forest in influencing the quality of –
Air :
(i) It helps in purifying the air by adding oxygen into it.
(ii) It takes carbon-dioxide gas during photosynthesis thus green-house effect is controlled.
(iii )Transpiration helps in the formation of clouds and thus, it maintains the temperature of surrounding area, giving cooling effect.

Soil :
(i) Plants in forest hold the soil. Thereby preventing soil erosion.
(ii) It holds the soil which helps in increasing the underground water level.
(iii) Adds nutrients to the soil due to lot of vegetation present in forest gets decomposed.

Water :
(i) Forest helps in bringing rain and increasing the level of water in underground levels.

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