Bihar Board Class 9th Science Book Solutions विज्ञान Chapter 14 Natural Resources- NCERT पर आधारित Text Book Questions and Answers Notes, pdf, Summary, व्याख्या, वर्णन में बहुत सरल भाषा का प्रयोग किया गया है.

Bihar Board Class 9 Science Solutions Chapter 14 Natural Resources

Question 1.
How is our atmosphere different from the atmospheres on Venus and Mars?
Answer:
Our atmosphere has various important gases like nitrogen, oxygen, carbon dioxide and water vapour which together help in the existence of life on it. But the atmospheres on Venus and Mars have 95% to 97% carbon dioxide. The life supporting gases are not present there.

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

It maintains average tempera-ture on the earth.
It prevents the sudden rise of temperature during daytime.
It prevents heat from escaping to the outer space during nights.
Question 3.
What causes winds?
Answer:
The air mass present near the earth surface get heated and rises up very fast. This leads to a decrease in air pressure. So, the heavier air present on the sea surface moves towards the area having low air pressure. This moving air causes wind.

Question 4.
How are clouds formed?
Answer:
The water vapourises in the water bodies due to sun’s heat. This water vapour mixed with the air. Some water vapours is already present in air. The water vapour, after cooling down forms small water droplets suspended in air. This is called cloud.

Bihar Board Class 9 Science Solutions Chapter 14 Natural Resources
Question 5.
List any three human activities that you think would lead to air pollution.
Answer:

Using fossil fuels likes diesel, petrol, kerosene, etc.
Burning woods and coals
Cement industry
Smoke from industries, etc.
Page 194

Question 1.
Why do organisms need water?
Answer:
The organisms need water :

For different cellular processes.
For transportation of substance from one place to another inside the body.
Question 2.
What is the major source of fresh water in the city/town/village where you live?
Answer:
Rivers or wells.

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

River : The river water bathing and cleaning pollute water.
Well : Bathing and cleaning pollute well water.
Page 196

Question 1.
How is soil formed?
Answer:
Following factors help in the formation of soil –
(i) Sun : The solar rays gradually heat the rock to expand it during day time. During nights, the rocks contract, thus the cracks develop in the rocks and they break down.
(ii) Water : Water helps in the formation of soil in two ways –
(a) The cracks formed due to solar heat are filled with water. If water accumulates for a longer time, it widens the gap and loosens the rock into small pieces,
(b) The blowing water carries away the small stone pieces and due to friction they further break down into more smaller pieces.
(iii) Air : Under the effect of blowing wind the stone pieces further break down.
(iv) Living organisms : Living organisms also help in the process of soil formation. Lichens grow on rock surfaces, converts them into powdery form and make soil layer. In the same way the plants like moss also help in the making of fine soil particles.

Bihar Board Class 9 Science Solutions Chapter 14 Natural Resources

Question 2.
What is soil erosion?
Answer:
The process of carrying away the upper fertile layer of soil by air and wind is called soil erosion.

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

To grow maximum crops
To prevent excessive grazing
To prevent felling down the tree and planting new trees
To maintain the fertility of the soil.
Page 201

Question 1.
What are the different states in which water is found during the water cycle ?
Answer:
Water is found in the following three different states during water cycle
(i) Solid (ice)
(ii) Liquid water
(iii) Gas (water vapour).

Question 2.
Name two biologically important compounds that contain both oxygen and nitrogen.
Answer:
(i) Protein
(ii) Nucleic acids (DNA and RNA).

Question 3.
List any three human activities which would lead to an increase in the carbon dioxide content of air.
Answer:
Following are sonde human activities responsible for an increase in carbon dioxide content of air.

Burning fossil fuels like diesel and petrol.
Burning firewood -and charcoal.
Felling down the trees.
Question 4.
What is greenhouse effect?
Answer:
The earth receives light of different wavelengths from the sun. The ozone present in the upper atmospheric layers absorbs the harmful ultra-violet rays. Earth receives other radiations and changes them/into infrared rays of higher wavelengths. C02 present in the atmosphere absorbs these radiations. This leads to an increase in the atmospheric temperature. This is called greenhouse effect.

Question 5.
What are the two forms of oxygen found in the atmosphere ?
Answer:
Oxygen is found in the following two form’s in the atmosphere—
(i) Diatomic state (O2)
(ii) Triatomic state (O3)

Bihar Board Class 9 Science Chapter 14 Natural Resources Textbook Questions and Answers
Question 1.
Why is the atmosphere essential for life?
Answer:
Importance of atmosphere :
(i) It maintains the temperature. If temperature on the earth rises suddenly, it may threaten the existence of life.
(ii) It prevents heat from escaping away to the outer space during nights.

Question 2.
Why is water essential for life?
Answer:
Importance of water :
(i) Water is essential for the biological processes taking place inside the cell.
(ii) It is essential for transportation of substances from one place to another inside the cell.

Bihar Board Class 9 Science Solutions Chapter 14 Natural Resources
Question 3.
How are living organisms dependent on the soil? Are organisms that live in water totally independent of soil as a resource ?
Answer:
Living beings directly or indirectly depend on soil because – All living being depend on green plants for their food and energy requirements. Carnivorous animals depend on herbivorous animals. Plants depend on soil because
(i) They obtain nutritive elejnents from soil for making their food.
(ii) Plant obtain water from soil. Soil also help them in standing erect and prevents them from being blown away by winds. This is not true to say that organisms living in water are totally independent of soil because they also depend on green plants for their food and energy requirements in one way or the other, plants in turn, are dependent on soil tor water and minerals. So, it can be said that all livjng beings whether aquatic or terrestrial directly or indirectly depend on soil.

Question 4.
You have seen weather reports on television and in newspapers. How do you think we are able to predict the weather?
Answer:
The prediction of weather can be done on the basis of speed and direction of wind which in turn help in predicting about the rain and other weather related processes. It helps in finding low or high air pressure areas . In India, most of the rains is due to south-west monsoon or north-east monsoon.

Question 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:
We know that many human activities increases pollution. But by limiting these activities to certain area would not reduce pollution. Air, water and soil are the natural resources which are interrelated. They cannot be limited to a certain area. Air is polluted with the rise in the level of CO2 and other air pollutants.

These air pollutants are carried away to other places by the winds. Water pollution is caused due to decrease in the level of oxygen dissolved in water and by adding toxic substances to various water bodied. This causes the death of aquatic life forms. This affects the food chain and food web. In the same way soil pollution leads to decrease in soil fertility and soil erosion. So, by limiting different human activities to specific areas the problem of pollution can’t be resolved.

Bihar Board Class 9 Science Solutions Chapter 14 Natural Resources
Question 6.
Write a note on how forests influence the quality of our air, soil and water resources.
Answer:
Forests influence all the three sources like air, water and soil :
(i) Forests maintain the balance between carbon dioxide and oxygen. They need CO2 for photosynthesis and release O2 in this process. Similarly they need O2 for respiration and release CO2 in this process.
(ii) Forests prevent soil erosion. The roots of plants hold soil tightly and prevent them from blown away by wind and water.
(iii) Forests are also essential for recharging the water sources. They play important role in maintaining, water cycle by transpiration. They also help in the cycling of under-ground and surface water. In this way forests affect the quality of air water and soil.

Bihar Board Class 9 Science Chapter 14 Natural Resources Additional Important Questions and Answers
Question 1.
What two things are essential for existence of life on the earth? ,
Answer:
(i) The sources like soil, air and water.
(ii) The energy produced by the sun.

Question 2.
What is biosphere?
Answer:
The life supporting zone of the earth where the atmosphere, the hydrosphere and the lithosphere interact and make life possible, is called biosphere.

Question 3.
What are the important components of biosphere?
Answer:
(i) Biotic components which include animals and plants.
(ii) Abiotic components like air, water, light etc.

Question 4.
What is atmosphere?
Answer:
‘The air mass surrounding the earth is called .atmosphere.

Question 5.
What are the main compo-nents of atmosphere?
Answer:
The main components of atmosphere are, nitrogen, oxygen, carbon dioxide apd water vapour.

Question 6.
The earth has life on it which is not present on Mars and Venus. Why?
Answer:
It is the presence of air-and water on the earth which makes the existence of life possible on it. While these components are not present on Mars and Venus.

Bihar Board Class 9 Science Solutions Chapter 14 Natural Resources
Question 7.
What is air?
Answer:
Air is a mixture of a number of gases.

Question 8.
Name the major gases present in air.
Answer:
Nitrogen, oxygen and carbon dioxide are the major gases present in air.

Question 9.
Write the major uses of oxygen.
Answer:
Following are the major uses of oxygen –
(i) It is necessary for respiration in living beings.
(ii) It helps in the burning of the fuel.

Question 10.
Name two such gases present in air which together constitute 80-90% part of air.
Answer:
Nitrogen and oxygen.

Question 11.
Name the process which help the balance bpjfween oj^ygen and carbon dioxide in the environment.
Answer:
Photosynthesis.

Question 12.
Name some gases and other substances which pollute air.
Answer:
SO2, CO2, oxides of nitrogen, H2S, dust particles, unburnt carbon particles, lead, asbestos, and cement, etc.

Question 13.
What is percentage of oxygen and nitrogen in air ?
Answer:
Oxygen – 21%, Ndtrogen – 78%.

Question 14.
How is carbon dioxide fixed?
Answer:
Carbon dioxide is fixed by following Vwo methods –
(i) By the process of photosynthesis.
(ii) Carbonates dissolved in water is used by some animals to make their shells.

Question 15.
What is percentage of COa present on Mars and Venus ?
Answer:
95 to 97%.

Question 16.
What is role of atmosphere in controlling the climate?
Answer:
The atmosphere prevents the sudden rise of temperature during daytime. During nights, it jprevents the heat from escaping away to the outer space.

Question 17.
What factors are respon-sible for change in the atmosphere?
Answer:
(i) Increase in the air temperature.
(ii) Formation of water vapour. —

Question 18.
What is the reason of wind blowing from sea to landmass during daytime?
Answer:
During daytime, the landmass is heated more rapidly than sea water. Hence the hot air on the land rises up very fast and lowers down the temperature. This is the reason the winds blow from sea towards landmass.