NCERT Exemplar Class 7 Science Chapter 16 Water A Precious Resource

NCERT Exemplar Class 7 Science Chapter 16 Water A Precious Resource are part of NCERT Exemplar Class 7 Science. Here we have given NCERT Exemplar Class 7 Science Solutions Chapter 16 Water A Precious Resource.

NCERT Exemplar Class 7 Science Solutions Chapter 16 Water A Precious Resource

Multiple Choice Questions

Question 1.
Which of the following does not show water shortage?
(a) Taps running dry
(b) Long queues for getting water
(c) Marches and protests for demand of water
(d) A family gets three buckets of water per person per day
Solution:
(d) The United Nations has re-commended that a minimum of 50 litres of water should be available to each of us per person per day for drinking, washing, cooking and cleaning. This amount is about two and a half buckets of water per person per day. Therefore, a family getting three buckets of water per person per day does not show water shortage.

Question 2.
Seas and oceans are full of water on earth. However, a very small percentage of water present on earth is available for us. This percentage is roughly
(a) 0.006%
(b) 0.06%
(c) 0.6%
(d) 6%.
Solution:
( c) About 97.4% of the total water on earth is in seas and oceans. About 2% water is frozen in glaciers and in polar ice caps. The remaining i.e., only 0.6% is available as freshwater in the liquid form. Even out of this 0.59% is present as groundwater and only 0.01% is available as freshwater on the surface of the earth.

Question 3.
Which of the following are not the liquid forms of water?
(i) Snow
(ii) Lake water
(iii) River water
(iv) Water vapour
(v) Ice
Choose the correct combination from the options below.
(a) (i), (iv) and (v)
(b) (i) and (ii)
(c) (ii) and (iii)
(d) (iv)only
Solution:
(a) Snow and ice are solid forms whereas water vapour is gaseous form of water.

Question 4.
A man digging the ground near a water body found that the soil was moist. As he kept digging deeper and deeper he reached a level where all the spaces between particles of soil and gaps between rocks were filled with water. The upper limit of this layer is called
(a) water level
(b) water table
(c) groundwater
(d) water limit.
Solution:
(b) If we dig a deep hole in the ground, soil below is moist. This shows the presence of water under the ground. If we go on digging deeper and deeper we will reach the level where all the spaces between the soil particles and the gaps between rocks are filled with water. The upper limit of this layer is known as the water table. This water table varies from place to place. At some places it may be less than a metre deep while at other places it may be as deep as 100 metres or more.

Question 5.
Which of the following is a way to use water economically?
(a) Construction of bawris
(b) Rainwater harvesting
(c) Drip irrigation
(d) Infiltration
Solution:
(c) In drip irrigation, water is allowed to fall drop by drop from a pipe, just near the roots of plants. So, this minimises wastage of water.

Question 6.
On which of the following day is World Water Day observed?
(a) 22 March
(b) 14 November
(c) 2 October
(d) 21 December
Solution:
(a)

Question 7.
The amount of water recommended by the United Nations for drinking, washing, cooking and maintaining proper hygiene per person per day is a minimum of
(a) 5 litres
(b) 15 litres
(c) 30 litres
(d) 50 litres.
Solution:
(d) Refer to answer 1.

Question 8.
Every Drop Counts” is a slogan related to
(a) counting of drops of any liquid
(b) counting of water drops
(c) importance of water
(d) importance of counting.
Solution:
(c)

Question 9.
Water cycle does not involve which of the following?
(a) Evaporation
(b) Condensation
(c) Formation of clouds
(d) Rainwater harvesting
Solution:
(d) Water constantly moves from the earth to the atmosphere and comes back to the earth again. This constant circulation of water in nature is known as the water cycle. Water cycle does not involve rainwater harvesting. In water cycle water in seas, rivers, lakes, ponds, or streams evaporates and water vapour rises up (evaporation). The air higher up in the atmosphere is cooler. This cools the water vapour and it condenses to form tiny drops of water (condensation). These drops of water unite together and form clouds (cloud formation). As the clouds get cooled further, more water drops unite together and become bigger. When they become too heavy, they fall on the earth as rain (precipitation).

Question 10.
Which of the following inhibits the seepage of rainwater into ground?
(a) A pukka floor
(b) Playground
(c) Grass lawn
(d) Forest land
Solution:
(a) A paved floor or pukka floor does not allow water to seep into the ground easily, whereas on a playground, grass lawn and forest land, water seeps through in no time.

Very Short Answer Type Questions

Question 11.
State whetherthefollowingstatementsareTrue or False. If false, write the correct statement.
(a) Water vapour is the gaseous form of water.
(b) Ice is solid whereas snow is the semi-solid form of water.
(c) Ocean water cannot be used for domestic purposes.
(d) Rapid growth of industries is one of the causes for water shortage.
Solution:
(a) True
(b) False – Snow is also a solid form of water.
(c) True
(d) True

Question 12.
Some definitions are given below which can be corrected by changing one word. Correct them.
(a) Aquifer is groundwater stored between layers of hard rock above the water table.
(b) The process of evaporation of water in the ground is called infiltration.
(c) The evaporation of water from oceans and its arrival back into oceans is called vapour cycle.
Solution:
(a) Aquifer is groundwater stored between layers of hard rock below the water table.
(b) The process of seepage of water in the ground is called infiltration.
(c) The evaporation of water from oceans and its arrival back into oceans is called water cycle.

Question 13.
What is the source of water in each of the following?
(a) Wells
(b) Ground
(c) Atmosphere
Solution:
(a) Wells – Groundwater
(b) Ground – Rain
(c) Atmosphere – Evaporation

Question 14.
State whether the following statements are true or False. If false, give the correct statement.
(a) The process of seeping of water into ground is called filtration.
(b) 51% of the earth’s surface is covered with water.
(c) Year 2003 was observed as the International Year of Freshwater.
(d) Snow and ice both are solid forms of water.
Solution:
(a) False. The process of seeping of water into ground is called infiltration.
(b) False. 71% of earth’s surface is covered with water.
(c) True
(d) True

Short Answer Type Questions

Question 15.
Fill in the blanks in the given passage.
The rainwater and _____ from other sources such as rivers and ponds seeps through the _____ and fills the empty spaces and cracks deep below the ground. The process of seeping of water into the ground is called _____.
Solution:
water, soil, infiltration

Question 16.
Fill in the blanks and complete the story selecting words from the box given here.
[ cold, demand, leaders, dry, hot, scarcity, workers, wet, oceans, harvesting, rivers ]
Rajasthan is a _____ and dry place. The challenge of natural _____ of water was met by a successful experiment. A band of social _____ had transformed a _____ area into a green place.They have revived five dried- up _____ by constructing water _____ structures.
Solution:
hot, scarcity, workers, dry, rivers, harvesting

Question 17.
Place the following statements in a proper order to form a meaningful paragraph.
(a) Which in turn decreases the seepage of rain water into the ground.
(b) This decreases the open areas like parks and playgrounds.
(c) Increasing population creates demand for construction of houses, shops, offices, roads and pavements.
(d) This results in depletion of water table and creates scarcity of more water.
Solution:
The correct arrangement of the given statements to form a meaningful paragraph is as follows:
(c) Increasing population create demand for construction of houses, shops, offices, roads and pavements.
(b) This decreases the open areas like parks and playgrounds.
(a) Which in turn decreases the seepage of rain water into the ground.
(d) This results in depletion of water table and creates scarcity of more water.

Question 18.
How can you observe the three forms of water
(i) in nature and
(ii) at home?
Solution:
(i) In nature, we can observe the solid form of water as falling snow, hails etc. We can observe the liquid form of water as rain or in water bodies such as rivers, lakes, oceans etc. Although we cannot see water in its gaseous state in nature, but we can feel it in the air on a hot, humid day.
(ii) At home, we can observe the three forms of water as ice (solid), water (liquid) and steam (gaseous).

Question 19.
Complete the given table

Form of water	Process by which formed	Location where found
(a) Liquid
(b) Solid
(c)Gaseous

Solution:

Form of water	Process by which formed	Location where found
(a) Liquid	Condensation, Melting	Water bodies like oceans, seas, rivers, lakes, etc.
(b) Solid	Freezing	Cold regions like high mountains, poles, glaciers etc.
(c) Gaseous	Evaporation	Atmosphere

Question 20.
Match column I with column

Column I		Column II
(a)	Groundwater	(i)	Solid form of water
(b)	Bawri	(ii)	Wastage of water
(c)	Snow	(iii)	Water management
(d)	Drip irrigation	(iv)	Small water
(e)	Leaking taps	(v)	Water table

Solution:
(a) (v)
(b) (iv)
(c) (i)
(d) (iii)
(e) (ii)

Question 21.
A list of jumbled words is given here. Write the correct form of each word.
(a) WASHFERRET
(b) CHARREGE
(c) QUIFERA
(d) WOSN
Solution:
(a) FRESHWATER
(b) RECHARGE
(c) AQUIFER
(d) SNOW

Question 22.
From where do the following usually get water? In which form is water present in them?
(a) Clouds
(b) Plants
(c) Mountain tops
(d) Aquifer
(e) Animals
Solution:
(a) Clouds get water from the atmosphere. Water in the clouds is present in liquid form as droplets of water.
(b) Plants get water from the soil. In plants, water is present in liquid form.
(c) Mountain tops get water from the atmosphere. Water on mountain tops is present in solid form i.e. in the form of snow or ice.
(d) Aquifer gets water from rain. Water in an aquifer is present in liquid form as underground water.
(e) Animals get water from water bodies such as oceans, rivers etc. In animals, water is present in liquid form.

Long Answer Type Questions

Question 23.
Complete the following chart by writing appropriate words in the boxes marked (a) to (e).

Solution:
(a) Solid
(b) Gaseous
(c) Well
(d) Lake
(e) Ice

Question 24.
What is groundwater? What are the sources of water which are fed by groundwater?
Solution:
Water found below the water table or underground water is known as groundwater.
Well, lake, pond, spring, hand pump, etc. are the sources of water which are fed by groundwater.

Question 25.
Water is very precious for all the living beings. What will happen in future if we do not save water now?
Solution:
Water is the gift of nature, we must learn to honour. If we do not use water judiciously and do not save it, there will be scarcity of water and we will not be able to do various activities where water is required. It will also affect life on earth. Some of the problems that would be faced by people due to water scarcity are:
(i) Daily activities will become very difficult in the shortage of water.
(ii) Crop production will be affected resulting in insufficient supply of food.
(iii) People would have to buy water at high prices.
(iv) People may drink dirty (contaminated) water which causes water-borne diseases such as cholera.
Due to water scarcity, sufficient water will not be available to plants. Plants need water to prepare their food by the process of photosynthesis. If water is not available to plants, the green character of the planet will be lost. This may mean the end of all life, for a world without plants will mean no food, no oxygen, not enough rain, and innumerable other problems.

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