CBSE Class 6 Science Water Worksheet Set A

ACTIVITY-1: To estimate the quantity of water used.

6- Short Answer Type Questions.

Answer : Water cycle is a cyclic process in which water is circulated between the earth and the atmosphere. In the presence of sunlight, water from water bodies like ocean, lakes, rivers etc. evaporates. This process is known as evaporation. These water vapours make clouds at heights by condensation. From clouds water falls back to earth in form of rain and snow.

 

(iii) Why there is need to conserve water? Write techniques of rain water harvesting.

Answer : Fresh clean water is available in limited amount. With rising population, the demand of water is increasing day by day. So it is the need to conserve water and use it carefully.

Techniques of rain water harvesting- (1). Rain water is collected on the roof of the house or building. It is then stored in storage tanks. This water can be used as per requirement.

(2). Rainwater is allowed to go into the ground directly to recharge ground water.

More Question- 

Q1) List various uses of water.

Q2) Name some sources of water.

Q3) How much portion of the earth is covered with water?
(a) about two third                        
(b) about three fourth
(c) about one fourth                      
(d) about one third

Q4) What is saline water?

Q5) Sea water cannot be used for domestic use because it contains
(a) soluble salts                              
(b) dust
(c) insoluble salts                        
(d) acids

Q6) Why do water drops appear on the outer surface of a glass containing cold water?

Q7) The process by which plants lose water is
(a) photosynthesis                          
(b) transpiration
(c) none of these

Q8) Explain water cycle. Support your answer with a figure.

Q9) How are clouds formed?

Q10) Name the processes by which water vapour is added to the atmosphere.

Q11) Define (a) Evaporation and (b)Transpiration

Q12) What is ground water?

Q13) Explain what happens if it rains heavily in a particular place?

Q14) What happens if it doesn’t rain for a long period in a particular region?

Q15) Why should we use water carefully ?

Q16) What is rain water harvesting?

Q17) Explain the two techniques of rainwater harvesting.

Q18) Fill in the blanks

a. Water vapour gets added to air by __________and __________.

b. Excessive rains may cause __________while lack of it for long periods may cause _________.

c. The water in the __________and __________is saline.

d. Nearly __________litres of water is lost through transpiration by wheat plants that give us one kilogram of wheat.

e. About _________ glasses of water are required to produce each page of a book.

Q19) List any three ways by which we can save water at home.

Q20) List any three ways by which used water can be reused at home.

Q 21) Rohan observed that families from nearby localities bring loads of laundry to wash in the river everyday. The same water was being consumed by people living downstream. When he tried to stop people, they said that, water was a gift from nature. He  tried to explain that chemicals in soaps and detergents make water harmful for both human beings and aquatic life.
What values are shown by Rohan?

Question. At some places water coming from the underground contains a lot of dissolved minerals and is called
(a) Underground water
(b) Spring
(c) Natural water
(d) None of these
Answer : B

Question. Floods occur
(a) in those areas where it rains excessively
(b) in those areas where we have constructed large dams
(c) Both the above
(d) None of these
Answer : A

Question. The water vapours, that are formed by evaporation of sea water
(a) consist of pure water
(b) contain dissolved salts in it
(c) Both the above
(d) None of these
Answer : A

Question. Evaporation involves
(a) change of solid to vapour
(b) change of liquid to vapour
(c) change of solid to liquid
(d) change of vapour to liquid
Answer : B

Question. Evaporation of sea water
(a) takes place during day time
(b) takes place during night time
(c) takes place throughout day and night
(d) takes place only during noon
Answer : C

Question. The tap water is considered pure and fit for drinking. Pure water is tasteless but tap water has some taste. This taste in tap water is due to
(a) chemical treatment through which the water has to pass before its supply through taps.
(b) certain gases and salts dissolved in water that is supplied as tap water.
(c) Both (a) and (b)
(d) None of these
Answer : A

Question. If there are no rains at a place for a long time it results in
(a) floods
(b) drought
(c) either floods or drought
(d) None of these
Answer : B

Question. Water is available on the surface of earth in the form of oceans, seas, rivers, ponds, etc.
Approximately how much of the earth is covered with water?
(a) 1/3 part
(b) 2/3 part
(c) 1/2 part
(d) 1/4 part
Answer : B

Question. Ocean water reaches us
(a) by rivers
(b) by ponds
(c) by water cycle
(d) All of these
Answer : C

Question. Which of the following is an example of reuse of water to prevent its wastage?
(a) By reusing the water from washing clothes to cook
(b) By discharging factory waste in rivers and canals
(c) By discharging sewage and waste materials into oceans
(d) By reusing the water from washing clothes to wash floor
Answer : D

Question. In water cycle the process that takes place before rains is called
(a) Evaporation
(b) Condensation
(c) Precipitation
(d) Melting
Answer : B

Question. Ocean water is highly saltish and unfit for drinking purposes.
(a) Oceans play no role in supply of usable water
(b) Role of oceans in supply of usable water is quite important
(c) Both the above
(d) None of these
Answer : B

Question. Which of the following processes help in transfer of water to air?
(a) Evaporation
(b) Condensation
(c) Transpiration
(d) Both (a) and (c)
Answer : D

Question. In water cycle we studied that water enters in air by some processes. If we say that water vapours that enter the air by process ‘A’ and by ‘B’, gets converted into water droplets which of the following correctly identifies ‘A’ and ‘B’?
(a) A = evaporation
B = process of change of water vapours into liquid
(b) A = The process involved in the disappearance of water from plate kept in sunlight
B = The process by which a wheat plant loses water to the atmosphere
(c) A = The process by which forest plants lose water to the atmosphere
B = The process involved in the conversion of water vapours to liquid water
(d) (a) and (c) are correct
Answer : D

Question. Water cycle means
(a) carrying of water using bicycles
(b) carrying of sea water to land by rivers etc.
(c) carrying of tap water to our homes
(d) circulation of water between ocean and land
Answer : D

Question. The basic idea behind rain water harvesting is
(a) to harvest water
(b) to harvest crops
(c) to catch water where it falls
(d) All of the above
Answer : C

Question. Select the process that plays an important role in bringing water back to earth.
(a) Evaporation
(b) Condensation
(c) Transpiration
(d) None of these
Answer : B

Question. Water table refers to
(a) level of surface water
(b) level of sea water
(c) level of groundwater
(d) None of these
Answer : C

Question. Rain water harvesting refers to
(a) a method of collecting rain water for our immediate daily use
(b) a method of conservation of rains
(c) collecting rain water for later use
(d) All of the above
Answer : C

Question. Which of the following is not a form of precipitation?
(a) Hailstorm
(b) Snow
(c) Rain
(d) None of these
Answer : D

Question. Purest form of natural water is ________.
(a) sea water
(b) ground water
(c) rain water
(d) surface water
Answer : C

Question. The actual source of tap water, supplied by municipal corporation is
(a) river
(b) lake
(c) well
(d) All of these
Answer : D

Question. The sea water changes to water vapour
(a) by solar energy
(b) by heat of sun
(c) Both the above
(d) None of these
Answer : C

Question. Which of the following statement(s) is/are correct?
(a) Water is called ‘Elixir of Life’.
(b) Approximately 8 glasses of water is needed to produce a page of your book.
(c) About 75% of earth is covered with water.
(d) All of the above.
Answer : A

Question. Water cycle can be represented as

The process that occurs in step ‘A’ is called
(a) Evaporation
(b) Transpiration
(c) Condensation
(d) None of these
Answer : A

Question. Clouds are
(a) water vapours as such
(b) water vapours condensed to tiny droplets of water
(c) tiny droplets of water and dust particles
(d) All of the above
Answer : C

Question. Which natural disaster causes famine?
(a) Flood
(b) Earthquake
(c) Drought
(d) All of these
Answer : C

Question. What percentage of water is readily available to us?
(a) 3%
(b) 97%
(c) 60%
(d) 40%
Answer : A

Question. Clouds are formed
(a) when water vapours present in air get cooled and change into tiny liquid droplets
(b) by the process of evaporation of water vapours
(c) by the process of condensation of water vapours
(d) Both (a) and (c) are correct
Answer : D

Question. Water vapours enter the air (or atmosphere) by which of the following processes?
(a) Evaporation of ocean water
(b) Transpiration occurring in plants
(c) By evaporation of sweat of animals
(d) All of the above
Answer : D

Question. Hardness of water is due to presence of
(a) salts of calcium
(b) salts of magnesium
(c) Both (a) and (b)
(d) None of these
Answer : B

Question. Which of the following statement(s) is/are true?
(i) Rainwater contains dissolved gases.
(ii) Sea water contains dissolved salts.
(a) Both (i) and (ii) are true
(b) Only (i) is true
(c) Only (ii) is true
(d) None of these
Answer : A

Question. If various steps of water cycle are marked as below :
A for rains
B for evaporation of water
C for water in rivers and lakes
D for cloud formation
If we take B as the first step in water cycle then the correct arrangement of letters A, B, C and D to correctly represent the water cycle will be
(a) B, D, A, C
(b) B, A, C, D
(c) B, C, D, A
(d) B, D, C, A
Answer : A

Question. We cannot use seawater because
(a) sea water is salty
(b) sea water is polluted
(c) of high cost
(d) sea water cannot be transported
Answer : A

Question. Why is the presence of water vapours in air important?
(a) It is important for air to be moist.
(b) It is important for water cycle in nature.
(c) It is important as plant get their water from this source.
(d) None of these
Answer : B

Question. Aquatic plants take in oxygen from
(a) air in the atmosphere
(b) dissolved air in water
(c) do not need oxygen
(d) None of these
Answer : B

Write define from your book:-

Short question answers-

Question 1: Name the three states of water.
Answer : The three states of water are: (i) Ice (solid) (ii) Water (liquid) (iii) Water vapour (gaseous)

Question 2: Name the forms of water as it occurs in nature in the three states.
Answer : Water occurs in nature in solid state as ice, in liquid state as water and in gaseous state as water vapour.

Question 3: 'Evaporation of water occurs at all temperatures.' How is evaporation dependent on temperature?
Answer : Evaporation of water occurs at all temperatures. As the temperature increases the rate of evaporation also increase.

Question 4: Why does water vapour condence when it reaches high up in the atmosphere?
Answer : The air gets cooler as it goes higher in the atmosphere. Because of the cooler air, the water vapour gets condensed when it goes higher in the atmosphere.

Question 5: When water vapour condence, it forms tiny drops of water that form clouds. When do these droplets come down as rain?
Answer : Water vapour condenses to form tiny droplets that form clouds. If there are dust particles in the clouds on which the water droplets can settle and get bigger, then the droplets will eventually become large enough to fall as rain drops.

Question 6: How can you change (a) water to ice? (b) ice to water? (d) water vapour to water?
Answer : (a) Water can be changed to ice by reducing the temperature. This is known as freezing of water. (b) Ice can be changed to water by heating it. This is known as melting of ice. (c) Water vapour can be changed to water by cooling the water vapour. This is known as condensation.

Question 7: How are natural springs of water formed?
Answer : The ground water which passes along the surface of the non porous rocks, however, at some places come out on the surface, forming a natural spring.

Question 8: Give any three important uses of water.
Answer : Following are the uses of water:
1. Water is extensively used for all domestic purposes like drinking, washing, cooking etc.
2. Water is one of the important mediums of transportation.
3. Water a source of energy to produce electricity.

Question 9: What do you mean by the 'water cycle'?
Answer : The cycle which involves the constant circulation of water from earth to atmosphere, and again back to the earth is called as water cycle.

I.Fill in the blanks:

1.The process by which plants evaporate water is called _________________.

2.The major natural source of water is _________________.

3. Water vapour gets added to the atmosphere by __________________ and ___________________.

4.Water disappears from wet clothes by the process of ___________________.

5. The source of water below the ground such as wells, tubewells, lakes etc. is known as _____________________.

6. In winter mornings , ____________is formed due to condensation of water vapour near the ground.

7. Many tiny water droplets high up in the air, come together and fall down as _____________, __________ and ___________.

8. The amount of the seepage of _____________ into the ground affects the availability of ground water.

II. Name the following:

1.Two natural sources of water.

2. Two fresh water bodies.

3.Two rainwater harvesting techniques

4.Four uses of water at home.

5. The two processes through which water vapour enters the air.

6. Two adverse effects of floods.

7. Two adverse effects of drought.

8. Two factors leading to shortage of usable water on the earth.

III. Write true or false:

1. Open wells are fed by ground water:

2. Life is possible on earth without water:

3. Saline water is fit for drinking and other domestic, agricultural and industrial needs:

4. Evaporation of water takes place at all times:

5. Concrete land surfaces increases the seepage of rainwater into the ground:

6. About two-thirds of the earth is covered with water.

7. When water is heated, it changes into ice.

IV. Define the following:

i. Water cycle.

ii. Rainwater harvesting.

V. Distinguish between: Evaporation and condensation.

VI. Assignment:

Draw, colour and label the water cycle.

Long question answers-

Question 1: Why is water so important for out body?
Answer : Water is important for our body because of the following reasons:
1. Water is a major constituent of all bodily fluids such as blood and plasma.
2. Water is essential for digestion of food, absorption of food and also excretion of wastes from the body.
3. Water is useful to cool the body and regulate temperature. When it is hot, we sweat from our skin.
4. A correct concentration of salts is maintained by water, which makes conduction of nerve impulses possible.

Question 2: In what ways is water useful to plants?
Answer : The utility of water to plants is as follows:
1. Water is required for the germination of seeds, their growth and development.
2. The roots of the plants absorb water from the soil. Along with carbon dioxide and water, plants prepare food in the presence of sunlight by photosynthesis.
3. This food is transported to various parts of the plants by means of water.

Question 3: How can you show that water vapour is present in air?
Answer : To demonstrate the presence of water vapour in air, take some ice cubes in a glass. Let the glass stand without being disturbed for some time. You will observe droplets of water on the outer surface of the glass. These water droplets result from the condensation of water vapour from the air on the cold surface of the glass. This shows that water vapour is present in air.

Question 4:  What are the reasons for lowering of the water table in large cities?
Answer : The water table in large cities has been lowered because of the following reasons:
1. In large cities, trees have been felled to make room for buildings and roads causing less rainfall in large cities.
2. In large cities, rain water is diverted by drains into lakes and reservoirs, rather than into the water table.
3. The large population in big cities uses ground water and other water resources faster than they can be replenished.

Question 5: During a drought, the prices of grain, fruits and vegetables go up. Why do you think this happens? Do you expect the prices of grain, fruits and vegetables to go up during floods also? Why?
Answer : Drought is a situation which occurs due to the shortage of rainfall.This results in drying up of crops, which in turn leads to the shortage of food. Hence, during drought, the prices of grains, fruits and vegetables increase. Floods are caused due to excess rainfall. Due to the excess water flow, the crops gets damaged again resulting in the shortage of food. Again, this causes an increase in food prices.

Question 6: What are the causes of floods?
Answer : During monsoon season, most parts of our country receives heavy rainfall. The rivers which are perennial, receive a very large amount of water. This causes the rivers to overrun their banks and move towards land, causing floods. In coastal areas, floods are often caused by tidal waves, which occur due to cyclones.

Question 7: List four ways in which we can conserve water.
Answer : Following are the ways by which we can conserve water and use it effectively: (i) Using the water effectively, by avoiding wastage and recycling wherever possible. (ii) Planting more trees and forestation. Trees absorbs water from the ground. Hence, balance the water cycle. (iii) Storing rain water in large amounts for future use by constructing dams.
(iv) Treating the sewage and industrial wastes before disposing them to the water source, thereby reducing the water pollution.

Question 8: Big dams have their own problems. Discuss.
Answer : Big dams have large water reservoirs to store a huge amount of water at a time. If the rainfall is heavy and the water exceeds the storage limit of the reservoir, then water is released from the dam. This causes heavy flooding, which destroys wildlife, agriculture and displaces people from their homes. Also, large amount of water stored in dams can cause earthquakes in regions prone to tectonic activity.

Question 9: What is rainwater harvesting? What are the two ways in which it can be done?
Answer : Rain water harvesting is storing the rain water for future use. Rain water harvesting can be done in following two ways: (i) The rain water that falls on the roof of the buildings are directed towards a deep pit in the ground. In this way the ground absorbs the water and thereby adding to the underground water reserves. (ii) Instead of allowing the rainwater to flow into the drains, the rain water has to be directed to the underground pits to again boost ground water levels.