Q1Multiple choice
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
Show answer
(d) re-radiated by land and water
Chapter 14
Class 9 Science · 56 questions · 56 with answers
Questions
Q2Multiple choice
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
Show answer
(c) increase during day and decrease during night
Q3Multiple choice
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.
Show answer
(b) It will become poisonous and kill living forms
Q4Multiple choice
One of the following factors does not lead to soil formation in nature
- (a)the sun
- (b)water
- (c)wind
- (d)polythene bags
Show answer
(d) polythene bags
Q5Multiple choice
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 16-04-2018
Show answer
(c) ozone and oxygen
Q6Multiple choice
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
Show answer
(b) elemental form of oxygen
Q7Multiple choice
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
Show answer
(b) the number of water bodies in an area
Q8Multiple choice
Among the given options, which one is not correct for the use of large amount of fertilisers and pesticides?
- (a)They are eco-friendly
- (b)They turn the fields barren after some time
- (c)They adversally affect the useful component from the soil
- (d)They destroy the soil fertility
Show answer
(a) They are eco-friendly
Q9Multiple choice
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
Show answer
(a) a biological process of nitrogen fixing bacteria present in soil
Q10Multiple choice
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
Show answer
(d) photosynthesis
Q11Multiple choice
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
Show answer
(c) A change in pressure of the water bodies
Q12Multiple choice
Which of the following is not a green house gas?
- (a)Methane
- (b)Carbon dioxide
- (c)Carbon monoxide
- (d)Ammonia 16-04-2018
Show answer
(d) Ammonia 16-04-2018
Q13Multiple choice
Which step is not involved in the carbon-cycle?
- (a)Photosynthesis
- (b)Transpiration
- (c)Respiration
- (d)Burning of fossil fuels
Show answer
(b) Transpiration
Q14Multiple choice
‘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
Show answer
(b) thinning of the ozone layer
Q15Multiple choice
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.
Show answer
(c) excessive use of man-made compounds containing both fluorine and chlorine
Q16Multiple choice
Which of the following is a recently originated problem of environment?
- (a)Ozone layer depletion
- (b)Green house effect
- (c)Global warming
- (d)All of the above
Show answer
(d) All of the above
Q17Multiple choice
When we breathe in air, nitrogen also goes inside along with oxygen. What is the fate of this nitrogen?
- (a)It moves along with oxygen into the cells
- (b)It comes out with the CO 2 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.
Show answer
(b) It comes out with the CO 2 during exhalation
Q18Multiple choice
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.
Show answer
(d) Humus, living organisms and soil particles.
Q19Multiple choice
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 NA T URAL RESOURCES 81 16-04-2018
Show answer
(b) CO2 in atmosphere → organic carbon in plants → organic carbon in animals → inorganic carbon in soil
Q20Multiple choice
Major source of mineral in soil is the
- (a)parent rock from which soil is formed
- (b)plants
- (c)animals
- (d)bacteria
Show answer
(a) parent rock from which soil is formed
Q21Multiple choice
Total earth’s surface covered by water is
- (a)75%
- (b)60%
- (c)85%
- (d)50%
Show answer
(a) 75%
Q22Multiple choice
Biotic component of biosphere is not constituted by
- (a)producers
- (b)consumers
- (c)decomposer
- (d)air
Show answer
(d) air
Q23Multiple choice
An increase in carbondioxide 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
Show answer
(d) abundance of desert plants
Q24Multiple choice
Oxygen is returned to the atmosphere mainly by
- (a)burning of fossil fuel
- (b)respiration
- (c)photosynthesis
- (d)fungi
Show answer
(c) photosynthesis
Q25Multiple choice
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
Show answer
(b) unburnt carbon particles or hydrocarbons suspended in air
Q26Multiple choice
Growth of Lichens on barren rocks is followed by the growth of
- (a)moss
- (b)ferns
- (c)gymnosperms
- (d)algae
Show answer
(a) moss
Q27Multiple choice
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. 16-04-2018
Show answer
(a) breeding of animals
Q28Multiple choice
Soil erosion can be prevented by
- (a)raising forests
- (b)deforestation
- (c)excessive use of fertilizer
- (d)overgrazing by animals
Show answer
(a) raising forests
Q29Multiple choice
What happens when rain falls on soil without vegetational cover?
- (a)Rain water percolates in soil efficiently
- (b)Rain water causes loss of surface soil
- (c)Rain water leads to fertility of the soil
- (d)Rain water does not cause any change in soil
Show answer
(b) Rain water causes loss of surface soil
Q30Multiple choice
Oxygen is harmful for
- (a)ferns
- (b)nitrogen fixing bacteria
- (c)chara
- (d)mango tree
Show answer
(b) nitrogen fixing bacteria
Q31Short answer
Rivers from land, add minerals to sea water. Discuss how?
Show answer
Water is capable of dissolving a large number of substances. As water flows over the rocks containing soluble minerals, some of them get dissolved in the water. Thus, rivers carry many nutrients from land to the sea.
Q32Short answer
How can we prevent the loss of top soil?
Show answer
Loss of top soil can be prevented by (i) increasing the vegetational cover (ii) checking the falling of trees (iii) by preventing excessive grazing by animals
Q33Short answer
How is the life of organisms living in water affected when water gets polluted?
Show answer
Addition of undesirable chemicals like pesticides, fertilizers, industrial waste and domestic wastes not only kill the organisms, they also cause diseases to the aquatic organisms. Besides, the requirement of oxygen by aquatic organisms is also increased. There is a reduction in the dissolved oxygen in water which adversely affects the aquatic organisms.
Q34Short answer
During summer, if you go near the lake, you feel relief from the heat, why?
Show answer
Hint— Air near water bodies is cooled due to evaporation of water.
Q35Short answer
In coastal area, wind current moves from the sea towards the land during day; but during night it moves from land to the sea. Discuss the reason.
Show answer
Hint— Air above the land gets heated quickly during day and starts rising. This creates a region of low pressure as a result air over sea rushes into this area of low pressure. This movment of air from one region to the other creates winds. During night, as water cools down slowly, the air above water is warmer than the air on land. So air moves from land to sea creating winds.
Q36Multiple choice
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 formation of soil? Write the mode of their action for making soil.
Show answer
Hint— Lichens and Mosses (a) and (b). Lichens and mosses release substances which break down the stones resulting in the formation of soil.
Q37Short answer
Soil formation is done by both abiotic and biotic factors. List the names of these factors by classifying them as abiotic and biotic?
Show answer
Abiotic factors making soil— sun, water, wind Biotic factors— lichens, mosses and trees
Q38Short answer
All the living organisms are basically made up of C, N, S, P, H and O. How do they enter the living forms? Discuss.
Show answer
Hint— Through photosynthesis and absorption from soil
Q39Short answer
Why does the percentage of gases like oxygen, nitrogen and carbon dioxide remain almost the same in the atmosphere?
Show answer
Hint— Cycling of these gases maintains consistency.
Q40Short answer
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? NA T URAL RESOURCES 83 16-04-2018
Show answer
Hint— Absence of atmosphere on the moon.
Q41Short answer
Why do people love to fly kites near the seashore ?
Show answer
Hint— Due to wind created during the day time
Q42Short answer
Why does Mathura refinery pose problems to the Taj Mahal?
Show answer
Mathura refinery releases toxic gases (like oxides of sulphur) which causes acid rain and hence corrosion of the marbles of Taj Mahal.
Q43Short answer
Why do not lichens occur in Delhi whereas they commonly grow in Manali or Darjeeling?
Show answer
Hint—It is a bio-indicator and sensitive to SO2 pollution from automobiles. Delhi has maximum number of automobiles, hence has a highly polluted environment.
Q44Short answer
Why does water need conservation even though large oceans surround the land masses?
Show answer
Hint—Marine water is not useful for human and plant life directly. Uneven distribution of limited fresh water resources need conservation to cater to the demands.
Q45Short answer
There is mass mortality of fishes in a pond. What may be the reasons ?
Show answer
Hint—(i) Thermal pollution (ii) Addition of poisonous (mercury) compounds in water (iii) Due to blockage of gills with any pollutant.
Q46Short answer
Lichens are called pioneer colonisers of bare rock. How can they help in formation of soil?
Show answer
Lichens release chemical substances to break the rocks into smaller particles and hence make soil.
Q47Short answer
“Soil is formed by water.” If you agree to this statement then give reasons
Show answer
Water helps in formation of soil in following ways (i) Water causes ‘wear off’ of rocks over a long period of time. (ii) It also causes the rocks to rub against other rocks creating small particles which are taken away downstream and deposited as soil. (iii) Water expands on freezing in crevices of rocks and cracks rocks into smaller pieces.
Q48Short answer
Fertile soil has lots of humus. Why?
Show answer
Fertile soils are rich in organisms that decomposes dead organic matter forming humus. Humus gives minerals, absorbs water and makes soil porous.
Q49Short answer
Why step farming is common in hills?
Show answer
Hint— This is practiced to check soil erosion through water currents on the slopes.
Q50Short answer
Why are root nodules useful for the plants?
Show answer
In root nodules nitrogen fixing Rhizobium bacteria are present which increases the soil fertility. Long Answer Questions
Q51Long answer
How do fossil fuels cause air pollution?
Show answer
The fossil fuels like coal and petroleum contain small amounts of nitrogen and sulphur. When fossil fuels are burnt, it produces oxides of nitrogen and sulphur. These gases cause inhalation problems and in presence of rain forms acid rain. Burning of fossil fuels also increase the amount of suspended particles in air that reduce the visibility.
Q52Long answer
What are the causes of water pollution? Discuss how you can contribute in reducing water pollution.
Show answer
Water pollution can be caused by addition of (i) undesirable substances like fertilizers and pesticides or any poisonous substances. (ii) sewage directly entring a water body. (iii) hot water from the power plant that increases the temperature and reduces the dissolved oxygen in water thus killing the aquatic organisms. (iv) industrial effluents or radioactive substances in water body. We can take following measures to check water pollution (i) The sewer lines should not be directly connected to the water body. (ii) We should not throw our garbages or domestic waste in the water body. (iii) Prevent dumping of toxic compounds in the water bodies. (iv) Washing of clothes should be avoided near water bodies as it adds lot of detergents to it. (v) Plant trees near the banks of the river to check soil erosion otherwise erosion leads to siltation of water body.
Q53Long answer
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?
Show answer
Infra-red radiations in sunlight pass through the glass and heat the interior of the car. The radiation emitted by upholstery and other inner parts of the car cannot pass out of the glass, so the heat trapped inside raises the temperature of the interior. This is because glass is transparent to infra- red radiation from the sun having smaller wavelength than that emitted by the interior of the car which are of longer wavelength to which the glass is opaque.
Q54Long answer
Justify “Dust is a pollutant” ?
Show answer
Dust remains present in air as suspended particles can cause allergy and other respiratory diseases. It also affects plant growth, by covering stomata on leaf surface. It acts as the carrier of toxic compounds like heavy metals.
Q55Long answer
Explain the role of the Sun in the formation of soil.
Show answer
Hint— The rocks are heated by the sun; they contract during night but not at same rate —resulting in cracks in rocks and ultimately to smaller particles.
Q56Long answer
Carbon dioxide is necessary for plants. Why do we consider it as a pollutant? 16-04-2018
Show answer
Hint— Increasing concentration (more than normal) of CO2 is harmful and considered as a pollutant. Higher concentrations of CO2 is one of the causes of green house effect/global warming. ANSWERS 149 C hapter 15 _lqucpq Multiple Choice Questions