# NCERT Exemplar Problems Class 6 Science – Water

## NCERT Exemplar Problems Class 6 Science – Water

Question 1:
Which of the following activities does not involve use of water?
(a) Washing clothes (b) Bathing
(c) Cleaning utensils (d) Drying wet clothes
Solution:
(d) Drying wet clothes is an activity which does not involve use of water.

Question 2:
In which of the following activities will you use minimum amount of water?
(a) Bathing (b) Brushing teeth (c) Washing clothes (d) Mopping a room
Solution:
(b) In brushing teeth we use minimum amount of water.

Question 3:
The quantity of water required to produce one page of your book is
(a) one bucket (b) ten buckets (c) two glasses (d) few drops
Solution:
(c) Two glasses of water is required to produce one page of our book.

Question 4:
Water in our tap comes from a
(a) river (b) lake (c) well (d) All of these
Solution:
(d) Water in our tap comes from river, lake or well.

Question 5:
In which of the following cases, evaporation of water will be slowest?
(a) A tray of water kept in sunlight (b) A kettle of water kept on a burner
(c) A glass of water kept in a room (d) A bucket of water kept on rooftop
Solution:
(c) The rate of evaporation increases on increasing the temperature and on increasing the surface area. A glass of water kept in a room has minimum surface area in the given options, so rate of evaporation will be slowest.

Question 6:
Transpiration is a process in which plants
(a) receive water from soil (b) absorb water vapour from air
(c) prepare food from water (d) release water in the form of water vapour
Solution:
(d) Transpiration is a process in which there is loss of water from plants as water vapour through the pores of their leaves.

Question 7:
Clouds are
(a) tiny drops of water floating in air (b) mixture of dust and water vapour
(c) particles of water vapour (d) rain drops in air
Solution:
(a) The mass of tiny droplets formed by the condensation of water vapour which we see floating high in the atmosphere is called a cloud.

Question 8:
Wells are fed by
(a) pond water (b) lake water
(c) rainwater (d) groundwater
Solution:
(d) Wells are fed by groundwater. The underground water can be taken out by digging a well into the ground. It is called well water.

Question 9:
Floods cause extensive damage to
(a) crops (b) property and human life
(c) domestic animals (d) All of these
Solution:
(d) Floods cause extensive damage to crop fields, villages and forests causing damage to property, human life, domestic animals, crops and wild animals of the forests.

Question 10:
‘Catch water where it falls’ is the basic idea behind
(a) recycling of water (b) making dams to store water
(c) rainwater harvesting (d) condensation of water vapour
Solution:
(c) ‘Catch water where it falls’ is the basic idea behind rainwater harvesting.

Question 11:
Look at the figure

Write down the activities shown in this figure in which water is being used.
Solution:
Activities shown in the above figure are :
(i) Washing clothes (ii) Bathing

Question 12:
Write any two activities which require more than a bucket of water.
Solution:
Two activities which require use of more than one bucket of water is washing more than 10 clothes and irrigating a crop field.

Question 13:
Write any two activities which require less than one bucket of water.
Solution:
Two activities which require use of less than one bucket of water is brushing teeth and washing a handkerchief,

Question 14:
Why do wet clothes placed on a clothes line dry after sometime? Explain.
Solution:
Wet clothes placed on a clothes line dry after sometime because water present in wet clothes is converted into water vapour and released in atmosphere due to evaporation which leaves them dry.

Question 15:
Water kept in sunlight gets heat from the sun and is evaporated. But how does water kept under the shade of a tree also gets evaporated? Explain.
Solution:
Water kept under the shade of a tree also evaporates because of warm air. Actually, during day time, the heat given out by the sun heats all the air around us. This warm air provides heat for evaporation of water kept in the shade.

Question 16:
How do the areas covered with concrete affect the availability of groundwater?
Solution:
Areas covered with concrete affect the availability of groundwater because concrete reduces the seepage of rainwater into the ground which leads to reduction in the availability of groundwater.

Question 17:
Why is there a need for conserving water? Give two reasons.
Solution:
There is a need for conserving water because of the following reasons:
(i) Increasing population is creating more demand for usable water.
(ii) Availability of freshwater is decreasing day-by-day.

Question 18:
Water, as ……… goes into atmosphere by the processes of ………. and ………. and forms ………. which on condensation fall in the form of ……… and ……… .
Solution:
vapours, evaporation, transpiration, clouds, rains, snow/hails

Question 19:
Most of the water that falls on the land as rain and snow, sooner or later goes back to a sea or an ocean. Explain how it happens.
Solution:
The process by which land water returns back to a sea or an ocean is as follows:
(i) Snow/Rain falling on the mountains melts into water that flows down in the form of streams and rivers.
(ii) A part of the rainwater gets absorbed into the ground and rest flow in the form of stream or rivers.
(iii) The river water after passing through various regions ultimately reaches into a sea or an ocean.

Question 20:
Draw a diagram to show how sea water reaches a lake or pond?
Solution:
Sea water reaches a lake or pond is represented by a diagram:

Question 21:
Dissolve two spoons of common salt in half a cup of water. Now, if you want to get the salt back, what will you do?
Solution:
The common salt dissolved in half a cup of water can be recovered by removing the water from the salt solution.
This can be done by heating the solution on a gas stove or keeping it under the sun in a plate for few hours.
Due to evaporation of water in both the processes, we will get the salt back.

Question 22:
Explain the process of rooftop rainwater harvesting with the help of a suitable diagram.
Solution:
The process of rooftop rainwater harvesting is as follows :
(i) In this process, the rainwater is collected on the rooftop.
(ii) This collected rainwater in allowed to pass through pipes into a storage tank at the ground level.
(iii) The collected water is filtered and used when required.

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