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NCERT
SOLUTIONS
CLASS - 7TH
aglase .co
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Book : Science Ncert Solutions | Chapter-16 Science
Class : 7th
Subject : Science
Chapter : 16
Chapter Name : Water: A Precious Resource
Q1 Mark ‘T’ if the statement is true and ‘F’ if it is false:
(a) The freshwater stored in the ground is much more than that present in the rivers and lakes
of the world. (T/F)
(b) Water shortage is a problem faced only by people living in rural areas. (T/F)
(c) Water from rivers is the only source for irrigation in the elds. (T/F)
(d) Rain is the ultimate source of water. (T/F)
Answer. (a) The freshwater stored in the ground is much more than that present in the rivers
and lakes of the world. (T)
(b) Water shortage is a problem faced only by people living in rural areas. (F)
(c) Water from rivers is the only source for irrigation in the elds. (F)
(d) Rain is the ultimate source of water. (F)
Q2 Explain how groundwater is recharged.
Answer. Rain water and the water from water bodies on earth's surface pass through the soil by
the process of in ltration. The in ltrated water then gets accumulated in the aquifer deep
under the ground. There are some layers of impermeable rocks which prevent the water in the
aquifer from seeping down further. In this way, the groundwater is recharged.
Q3 There are ten tube wells in a lane of fty houses. What could be the long term impact on
the water table?
Answer. If the people of the fty houses use the ten tube wells, then the water required by
them is drawn from the ground. If these tube wells are used for long time, then the ground
water would be reduced and the water table would go down.
Q4 You have been asked to maintain a garden. HOW will you minimise the use Of water?
Answer. To maintain a garden, water iS necessary. Therefore, to minimise the use of water, we
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Book : Science Ncert Solutions | Chapter-16 Science
can apply the drip irrigation meth0d. In this meth0d, water iS supplied directly to the base of
the Plants using narrow pipes, thereby reducing the loss Of water.
Q5 Explain the factors responsible for the depletion Of water table.
Answer. The factors responsible for the depletion Of water table are as follows:
(i)increasing population
As a result of increasing population, all the facilities such as houses, Shops, roads, Of ces,
pavements, etc. increase to ful l the increasing demands. This, in turn, decreases the open
area for seepage Of water into the ground.
(ii)increasing industries
Most of the stages of manufacturing processes in industries require water. If the number of
industries increases, then the water required by them will also increase. Therefore, increase of
industries contributes to the depletion of water table.
(iii)Agricultural activities
India is an agricultural country and agriculture is impossible without water. The water
for agriculture is mainly utilised from groundwater, rain water and canal water. As there is no
rainfall in many places, agriculture cannot be entirely depended on rain water. Also, canal
water is available in a few places only. Therefore, ground water is the main source of water for
agricultural activities and this causes depletion of water table.
Q6 Fill in the blanks with the appropriate answers:
(a) People obtain groundwater through________ and ________.
(b) Three forms of water are ________, ________ and ________.
(c) The water bearing layer of the earth is ________.
(d) The process of water seepage into the ground is called ________.
Answer. (a) People obtain groundwater through tube wells and banmpumps.
(b) Three forms of water are ice,water and vapour.
(c) The water bearing layer of the earth is aquifer.
(d) The process of water seepage into the ground is called in ltration.
Q7 Which one of the following is not responsible for water shortage?
(i) Rapid growth of industries
(ii) Increasing population
(iii) Heavy rainfall
(iv) Mismanagement of water resources
Answer. (iii) Heavy rainfall
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Book : Science Ncert Solutions | Chapter-16 Science
Page : 204 , Block Name : Exercise
Q8 Choose the correct option. The total water
(i) in the lakes and rivers of the world remains constant.
(ii) under the ground remains constant.
(iii) in the seas and oceans of the world remains constant.
(iv) of the world remains constant.
Answer. The total water
(iv) of the world remains constant.
Page : 204 , Block Name : Exercise
Q9 Make a sketch showing groundwater and water table. Label it.
Answer.
Page : 204 , Block Name : Exercise
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