NCERT Exemplar Solutions Class 9 Science Chapter 14 – Free PDF Download
NCERT Exemplar Solutions for Class 9 Science Chapter 14 Natural Resources provided here assist Class 9 students with their exam preparation. This NCERT Exemplar will help you learn the topics important for the final exam, thus boosting your preparation for the examination. Students of Class 9 are advised to refer to NCERT Exemplar Solutions from BYJU’S to gain a grip on the important concepts. The solutions are prepared with the main aim of helping students with their exam preparation. Step-wise explanations are given in simple language to prepare efficiently for exams.
This webpage comprises MCQs on natural resources with answers, short and long answer questions. Referring to NCERT Exemplar Solutions Class 9 Science during practice sessions aids in identifying the questions important for examinations. By solving these solutions, one can be thorough in all concepts present in NCERT Exemplar Solutions for Class 9 Science Chapter 14.
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Multiple Choice Questions
1. The atmosphere of the earth is heated by radiations which are mainly
(a) radiated by the sun
(b) re-radiated by land
(c) re-radiated by water
(d) re-radiated by land and water
Soln:
Answer is (d) re-radiated by land and water
Explanation:
Heat from the sun reaches the earth and water. This heat is re-radiated by earth and water that heats the atmosphere.
2. If there were no atmosphere around the earth, the temperature of the earth will
(a) increase
(b) go on decreasing
(c) increase during day and decrease during night
(d) be unaffected
Soln:
Answer is (c) increase during day and decrease during night
Explanation:
Because the atmosphere prevents a lot of heat from reaching the earth’s surface. The atmosphere also prevents the escape of heat during the night. Hence the atmosphere is responsible for maintaining an ambient temperature.
3. What would happen, if all the oxygen present in the environment is converted to ozone?
(a) We will be protected more
(b) It will become poisonous and kill living forms
(c) Ozone is not stable, hence it will be toxic
(d) It will help harmful sun radiations to reach earth and damage many life forms.
Soln:
Answer is (b) It will become poisonous and kill living forms
Explanation:
All the organisms living on earth require oxygen to live. If oxygen is converted to ozone, all the living beings will die.
4. One of the following factors does not lead to soil formation in nature
(a) the sun
(b) water
(c) wind
(d) polythene bags
Soln:
Answer is (d) polythene bags
Explanation:
Polythene bags pollute the soil and make it infertile.
5. The two forms of oxygen found in the atmosphere are
(a) water and ozone
(b) water and oxygen
(c) ozone and oxygen
(d) water and carbon-dioxide
Soln:
Answer is (c) ozone and oxygen
Explanation:
Ozone is an allotropic form of oxygen.
6. The process of nitrogen-fixation by bacteria does not take place in the presence of
(a) molecular form of hydrogen
(b) elemental form of oxygen
(c) water
(d) elemental form of nitrogen
Soln:
(b) elemental form of oxygen
7. Rainfall patterns depend on
(a) the underground water table
(b) the number of water bodies in an area
(c) the density pattern of human population in an area
(d) the prevailing season in an area
Soln:
Answer is (b) the number of water bodies in an area
Explanation:
Water bodies provide water for evaporation which is converted into clouds and bring rainfall. Lack of water bodies also reduces the humidity which will affect the rainfall pattern.
8. Among the given options, which one is not correct for the use of a large amount of fertilisers and pesticides?
(a) They are eco-friendly
(b) They turn the fields barren after some time
(c) They adversely affect the useful component from the soil
(d) They destroy the soil fertility
Soln:
Answer is (a) They are eco-friendly
9. The nitrogen molecules present in air can be converted into nitrates and nitrites by
(a) a biological process of nitrogen-fixing bacteria present in soil
(b) a biological process of carbon fixing factor present in soil
(c) any of the industries manufacturing nitrogenous compounds
(d) the plants used as cereal crops in field
Soln:
Answer is (a) a biological process of nitrogen-fixing bacteria present in the soil
Explanation:
Cereals cannot fix the nitrogen on their own. They comprise bacteria in their root nodules which will convert nitrates to nitrites. This process is called nitrogen fixation.
10. One of the following processes is not a step involved in the water-cycle operating in nature
(a) evaporation
(b) transpiration
(c) precipitation
(d) photosynthesis
Soln:
Answer is (d) photosynthesis
Explanation:
Photosynthesis is a part of the carbon cycle but not the water cycle.
11. The term “water-pollution” can be defined in several ways. Which of the following statements does not give the correct definition?
(a) The addition of undesirable substances to water-bodies
(b) The removal of desirable substances from water-bodies
(c) A change in pressure of the water bodies
(d) A change in temperature of the water bodies
Soln:
Answer is (c) A change in pressure of the water bodies
Explanation:
Physical causes lead to a change in pressure on water bodies. Hence the change in water pressure will not affect the pollution of water.
12. Which of the following is not a greenhouse gas?
(a) Methane
(b) Carbon dioxide
(c) Carbon monoxide
(d) Ammonia
Soln:
Answer is (d) Ammonia
13. Which step is not involved in the carbon cycle?
(a) Photosynthesis
(b) Transpiration
(c) Respiration
(d) Burning of fossil fuels
Soln:
Answer is (b) Transpiration
Explanation:
Transpiration is the process of exhaling water from trees. Transpiration is a part of water cycle.
14. Ozone-hole means
(a) a large sized hole in the ozone layer
(b) thinning of the ozone layer
(c) small holes scattered in the ozone layer
(d) thickening of ozone in the ozone layer
Soln:
Answer is (b) thinning of the ozone layer
15. Ozone-layer is getting depleted because of
(a) excessive use of automobiles
(b) excessive formation of industrial units
(c) excessive use of man-made compounds containing both fluorine and chlorine
(d) excessive deforestation.
Soln:
Answer is (c) excessive use of man-made compounds containing both fluorine and chlorine
Explanation:
Carbon and fluorine react with ozone to convert it into oxygen. This results in thinning of the ozone layer which is called ozone depletion.
16. Which of the following is a recently originated problem of environment?
(a) Ozone layer depletion
(b) Greenhouse effect
(c) Global warming
(d) All of the above
Soln:
Answer is (d) All of the above
17. When we breathe in air, nitrogen also goes inside along with oxygen. What is the fate of nitrogen?
(a) It moves along with oxygen into the cells
(b) It comes out with the CO2 during exhalation
(c) It is absorbed only by the nasal cells
(d) Nitrogen concentration is already more in the cells so it is not at all absorbed.
Soln:
Answer is (b) It comes out with the CO2 during exhalation
Explanation:
Nitrogen is the most abundant gas in nature hence while inhalation nitrogen goes inside our body along with oxygen. But it is not utilized by our body and is exhaled along with carbon dioxide.
18. Top-soil contains the following
(a) Humus and living organisms only
(b) Humus and soil particles only
(c) Humus, living organisms and plants
(d) Humus, living organisms and soil particles.
Soln:
Answer is (d) Humus, living organisms and soil particles.
19. Choose the correct sequences
(a) CO2 in atmosphere → decomposers → organic carbon in animals → organic carbon in plants
(b) CO2 in atmosphere → organic carbon in plants → organic carbon in animals → inorganic carbon in soil
(c) Inorganic carbonates in water → organic carbon in plants → organic carbon in animals → scavengers
(d) Organic carbon in animals → decomposers → CO2 in atmosphere → organic carbon in plants
Soln:
Answer is (b) CO2 in atmosphere → organic carbon in plants → organic carbon in animals → inorganic carbon in soil .
Explanation:
Green plants utilize atmospheric carbon-dioxide during photosynthesis to make organic compounds. When animals eat plants organic compounds will go to animals. When plant or animals die they get decomposed to turn into inorganic carbon.
20. Major source of mineral in soil is the
(a) parent rock from which soil is formed
(b) plants
(c) animals
(d) bacteria
Soln:
Answer is (a) parent rock from which soil is formed
Explanation:
Rock weathering is a process which forms soil. Rocks are naturally occurring soil aggregates which are rich in minerals. Hence rock is the source of minerals in the soil.
21. Total earth’s surface covered by water is
(a) 75%
(b) 60%
(c) 85%
(d) 50%
Soln:
Answer is (a) 75%
22. Biotic component of biosphere is not constituted by
(a) producers
(b) consumers
(c) decomposer
(d) air
Soln:
Solution is (d) air
Explanation;
Biotic component of biosphere comprises living entities, the air is a non-living component hence air is not an abiotic component.
23. An increase in carbon dioxide content in the atmosphere would not cause
(a) more heat to be retained by the environment
(b) increase in photosynthesis in plants
(c) global warming
(d) abundance of desert plants
Soln:
Answer is (d) abundance of desert plants
Explanation:
Increase in CO2 content will not favour the growth of desert plants because plants also require, oxygen, minerals and water to grow and develop.
24. Oxygen is returned to the atmosphere mainly by
(a) burning of fossil fuel
(b) respiration
(c) photosynthesis
(d) fungi
Soln:
Answer is (c) photosynthesis
Explanation:
Plants take CO2 from environment and they return back oxygen by a process called photosynthesis.
25. Low visibility during cold weather is due to
(a) formation of fossil fuel
(b) unburnt carbon particles or hydrocarbons suspended in air
(c) lack of adequate power supply
(d) none of these
Soln:
Answer is (b) unburnt carbon particles or hydrocarbons suspended in air
Explanation:
Unburnt carbon particles and Hydrocarbons suspend in the air to create smog. Because of smog visibility will be low in cold weather.
26. Growth of Lichens on barren rocks is followed by the growth of
(a) moss
(b) ferns
(c) gymnosperms
(d) algae
Soln:
Answer is (a) moss
Explanation:
Lichens release certain enzymes which makes the rock suitable for the growth of moss. Further moss leads to the formation of soil which will allow higher plants to grow.
27. Marked temperature changes in aquatic environment can affect
(a) breeding of animals
(b) more growth of aquatic plants
(c) process of digestion in animals
(d) availability of nutrients.
Soln:
Answer is (a) breeding of animals
Explanation:
Most aquatic animals are cold-blooded. Their egg and larvae are highly susceptible to temperature changes hence breeding of animals gets affected by temperature changes.
28. Soil erosion can be prevented by
(a) raising forests
(b) deforestation
(c) excessive use of fertilizer
(d) overgrazing by animals
Soln:
Answer is (a) raising forests
Explanation:
Trees in the forest hold on the soil by its roots. Hence growing forest can prevent soil erosion.
29. What happens when rain falls on soil without vegetational cover?
(a) Rainwater percolates in soil efficiently
(b) Rainwater causes loss of surface soil
c) Rainwater leads to fertility of the soil
(d) Rainwater does not cause any change in soil
Explanation:
b) Rainwater causes loss of surface soil
Explanation:
Roots hold on the surface soil and help them to get washed away from the current of water due to rainfall. When there is no vegetation surface soil gets washed away.
30. Oxygen is harmful for
(a) ferns
(b) nitrogen-fixing bacteria
(c) chara
(d) mango tree
Soln:
Answer is (b) nitrogen-fixing bacteria
Explanation:
Nitrogen-fixing bacteria are anaerobic, they get killed when exposed to oxygen hence oxygen is harmful to them.
Short Answer Questions
31. How do fossil fuels cause air pollution?
Soln:
When we burn fossil fuels carbon dioxide, nitrous oxide and other chemicals are released which increase the green-house effect and contribute to global warming. Nitrous oxide forms smog and results in acid rain.
32. How can we prevent the loss of topsoil?
Soln:
Loss of topsoil can be stopped by 1) Afforestation 2) Crop rotation 3) Counter farming 4) proper irrigation methods.
33. How is the life of organisms living in water affected when water gets polluted?
Soln:
Addition of pollutants like fertilizers and chemicals to the water bodies will cause diseases in aquatic organisms. Pollutants increase the biological oxygen demand of organisms living in water, since, the dissolved oxygen in the water reduces drastically.
34. During summer, if you go near the lake, you feel relief from the heat, why?
Soln:
Lake water gets evaporated and vapours formed due to evaporation create a cooling effect near lake. Hence we feel relieved from heat.
35. In coastal area, wind current moves from the sea towards the land during the day; but during the night it moves from land to the sea. Discuss the reason.
Soln:
During day time land heats more than the sea. This creates low pressure on the land and wind always moves from the region of low pressure to high pressure. Similarly in the night land cools faster and sea remains hot making wind to move from sea to land.
36. Following are a few organisms
(a) lichen
(b) mosses
(c) mango tree
(d) cactus
Which among the above can grow on stones; and also help in the formation of soil? Write the mode of their action for making soil.
Soln:
Answers are (a) lichen (b) mosses
Explanation:
Lichens grow on rocks and release certain enzymes which favour the growth of mosses. Mosses form clumps of soil from the rock which results in the formation of topsoil.
37. Soil formation is done by both abiotic and biotic factors. List the names of these factors by classifying them as abiotic and biotic?
Soln:
Abiotic factors;
Sun, water and wind
Biotic Factors:
Lichens, mosses and trees.
38. All the living organisms are basically made up of C, N, S, P, H and O. How do they enter the living forms? Discuss.
Soln:
C, N, S, P, H and O enters the living community through plants. Carbon comes through photosynthesis and nitrogen is obtained through nitrogen-fixing bacteria. Sulphur and Phosphorus are absorbed from the soil. Hydrogen and oxygen are obtained by water. These nutrients are obtained by animals from plants.
39. Why does the percentage of gases like oxygen, nitrogen and carbon dioxide remain almost the same in the atmosphere?
These gases are used by human beings for their growth and development. But these are returned to the environment in one or other form. This process of using natural resources and giving them back to nature is called a biogeochemical cycle. Because of the biogeochemical cycle percentage of gases like oxygen, nitrogen and carbon dioxide remain almost the same in the atmosphere.
40. Why does moon have very cold and very hot temperature variations eg., from -190°C to 110°C even though it is at the same distance from the sun as the earth is?
Soln:
Earth has an atmosphere which prevents overheating of the earth during day time. On the other hand, Moon does not have atmosphere hence it appears to be hotter during day time. Lack of atmosphere in the moon also allows the heat to escape during the night because of this phenomenon temperature varies on the moon surface.
41. Why do people love to fly kites near the seashore?
Soln:
Near the seashore, breeze blows during day time which is ideal for flying kites.
42. Why does Mathura refinery pose problems to the Taj Mahal?
Soln:
Mathura refinery releases oxides of Sulphur which causes acid rain. Acid rain corrodes the marble of Tajmahal hence Mathura refinery pose problems to Tajmahal.
43. Why do not lichens occur in Delhi whereas they commonly grow in Manali or Darjeeling?
Soln:
Lichens are sensitive to Sulphur oxide released by automobiles. Delhi has more number of automobiles which increases pollution. Pollution avoids lichens in Delhi.
44. Why does water need conservation even though large oceans surround the landmasses?
Soln:
Seawater is not suitable for the livelihood of humans and plants. Freshwater resources are limited hence they need to be conserved.
45. There is mass mortality of fishes in a pond. What may be the reasons ?
Soln:
Reasons for mortality of fishes in a pond are i) Thermal pollution ii) addition of mercuric compounds and other toxic chemicals iii) Blockage of gills by pollutants.
46. Lichens are called pioneer colonisers of bare rock. How can they help in the formation of soil?
Soln:
Lichens release enzymes that break the rock into smaller pieces and helps in the formation of soil.
47. “Soil is formed by water.” If you agree to this statement then give reasons
Soln:
Water causes soil formation by following steps.
- Water causes wear off of rock for a long period of time.
- Water makes rubbing between the rocks to smaller particles which are deposited as soil.
- On freezing, water expands to cause breaks in the rock.
48. Fertile soil has lots of humus. Why?
Soln:
Fertile soil has a number of microorganisms that decompose dead and organic matter to convert to humus. Humus provides nutrients, absorb water and makes soil porous.
49. Why step farming is common in hills?
Soln:
In hills, there are steep slopes which risk washout of topsoil by wind and rain. In order to conserve topsoil, step farming is done in hills.
50. Why are root nodules useful for the plants?
Soln:
Root nodules are the home for nitrogen-fixing bacteria called a Rhizobium. Rhizobium fixes atmospheric nitrogen thereby increasing soil fertility.
Long Answer Questions
51. How do fossil fuels cause air pollution?
Soln:
Fossil fuels like petrol, diesel and kerosene releases oxide of Sulphur, nitrogen and carbon. Sulphur and Nitrogen oxides cause acid rain.
Burning fossil fuels release carbon monoxide which increases the carbon-di-oxide in the atmosphere which will affect living organisms.
Burning of fuels increases the amount of suspended particles in the air which reduces visibility.
52. What are the causes of water pollution? Discuss how you can contribute in reducing water pollution.
Soln:
Causes of water pollution are given below
- Chemical Fertilizers and pesticides consist of poisonous chemical which reaches the water body to turn water into toxic.
- Dumping of sewage directly into water bodies
- Release of industrial effluents into water resources.
Below are the steps we can take to reduce water pollution
- Stop connecting sewage lines directly to water bodies.
- Avoiding throwing garbage and other domestic waste into the water resource.
- Prevent dumping of toxic chemical into water body.
- Avoid washing of clothes near water bodies.
53. A motor car, with its glass totally closed, is parked directly under the sun. The inside temperature of the car rises very high. Explain why?
Soln:
Infrared radiation emitted by the sun can pass the transparent glass and increases the temperature inside the car. These radiations have smaller wavelength than the radiations emitted by the car. For these waves, transparent glass remain opaque further increasing the temperature.
54. Justify “Dust is a pollutant”?
Soln:
Dust is a fine powder of tiny earth particles and waste matter. It is carried to the atmosphere by wind, dust causes allergy in humans and affects plant growth by blocking the stomata on the leaf surface. Dust also carries toxic substance from the environment to pollute the water bodies affecting the aquatic life.
55. Explain the role of the Sun in the formation of soil.
Soln:
Sunlight heats the rock in the afternoon which results in the expansion of rock. When it cools down in the night contraction takes place which is not at the rate of expansion. Because of this difference in the rate of expansion and contraction rock get cracked to form small rock particles.
56. Carbon dioxide is necessary for plants. Why do we consider it as a pollutant?
Soln:
Carbon dioxide is considered a pollutant because it is a green-house gas which is responsible for global warming. This results in a change of earth’s climate. Along with that excess CO2 is harmful to the plants. Increased CO2 levels change physiology, growth and chemistry of plants. High CO2 concentration also causes suffocation, hard breathing and choking issues.
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The Importance of CBSE Class 9 Science Chapter 14 Natural Resources
In this chapter, students will learn about natural resources like air, water, sunlight, different types of soils and their uses, the nitrogen cycle and the water cycle. To master the concepts of this chapter, students are advised to solve NCERT Exemplar Class 9 Science Chapter 14 Natural Resources. Click the above link to get the free PDF of Natural Resources Exemplar questions for Class 9.
Topics Covered in the NCERT Exemplar for Class 9 Science Chapter 14 Natural Resources
- The Breath of Life: Air
- The Role of Atmosphere in Climate Control
- The Movement of Air: Winds
- Rain
- Air Pollution
- Water: A Wonder Liquid
- Water Pollution
- Mineral Riches in the Soil
- Biogeochemical Cycles
- The Water-cycle
- The Nitrogen-cycle
- The Carbon-cycle
- The Oxygen-cycle
- Ozone Layer
Natural Resources is an important chapter from which many questions are asked in competitive examinations. Students who are planning to attempt competitive examinations in future should study this chapter well and understand the concepts clearly. Resource materials provided by BYJU’S will clear all your doubts on the chapter Natural Resources. In order to access the study materials we provide, log on to BYJU’S website or download BYJU’S – The Learning App.
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