CBSE Class 6 Science Water Worksheet Set C

Learning Objectives
1. Water is a natural resource.
2. Water cycle.
3. Role of transpiration, evaporation, vaporisation in water cycle.
4. Formation of hail, snow, precipitation and rains.
5. Sources of water.
6. Conservation of water. 

About three fourth of Earth’s surface is covered with water. Water is found in rivers, seas, oceans, soil, air, plants and animals. Man is dependent on plants and animals which are in turn dependent on air, water and soil etc. All such substances which are used by man for sustenance of life and his welfare are called resources and those that are found in nature are called natural resources.

Importance of water : Water is the most important substances required by us. Without water, we cannot live. Water is used in agriculture, industries, for washing, bathing, drinking, cooking, cleaning and several other purposes. Our body has 70% water by weight while water melon is 99% water.

Percentage of water in food and animals
1. Several life processes like digestion, excretion, absorption of nutrients and distribution required large quantity of water.
2. Water is the natural habitat for marine life.
3. Water is a universal solvent as it can dissolve may substances.
4. It is used in bathing, cleaning, washing, dyeing and other household purposes.
5. Water helps in dispersal of seeds and fruits.
6. It is used for generating steam in factories.
7. It is used in sports and recreation.
8. It is also used to generate hydroelectricity.
9. It is essential for germination of seeds and for photosynthesis.
10. Crops cannot grow without water.
11. Our body temperature is controlled by water.
12. It is also used as a mode of transportation.

STATES OF WATER
Water can exist in three states: solid, liquid and gas.
→ Ice is the solid form of water.
→ Water that we drink is the liquid state.
→ Steam is the gaseous state.
In nature, water is found in solid state as snow on high mountains. Most of water on earth is in liquid form found in rivers, seas, oceans and lakes. Water vapour in air is the gaseous state of water.
We can change the state of water by changing the temperature; either by heating or cooling.
Water can be changed to ice by cooling. This is called freezing.
When ice is heated it will melt to form water. This is called melting of ice. Similarly when water is heated, it forms steam. This is called evaporation.
Evaporation occurs at all temperature. Water from wet clothes evaporates and then clothes become dry. Wet clothes dry faster in the sun and water evaporates faster if the surface area is increased.
Water vapour condenses to form water on cooling. This is called condensation.

Water circulates in nature. The circulation of water from the surface of earth to the atmosphere and back to earth is called water cycle.
Water from water bodies like rivers, seas, oceans and lakes evaporates because of the heat of sun. Plants also give out water from their leaves during transpiration. Water vapour rises and as they reach higher up in the atmosphere they cool and condenses to form water droplets. These water droplets coalesce to from clouds. The clouds cool further and when they become too heavy, they fall down on earth as rain. This is called precipitation.
The rainwater falls on seas, rivers and other water bodies. Water from land also flows into rivers through streets. Some rainwater may seep underground as groundwater. This water is used in houses; agriculture and industries. Finally this water too goes into rivers and seas. Snow from mountains also melt and flows into rivers. The water in oceans, seas, rivers and lakes evaporate again.
This cycle goes on and in this way water cycle goes on in nature.

Fog : During winter, sometimes, condensation of water vapours start near the surface of earth. These condensed vapour do not form rain clouds. Instead they appear near the earth surface as fog.

Hail or snow : Sometimes when rain falls on high mountains or when it is too cold, the water becomes solid and becomes snow. When snow falls it is called hail.

Dew : During winter nights, when air becomes very cool, the vapours near the earth’s surface condense and form water droplets. These appear as dew on leaves, flowers, railings etc.

Sources of Water

Rainwater : Rain is the main source of water. It is free from germs but may contain dust particles. There are some dissolved gases such as carbondioxide and sometimes acids may also pollute rain water causing acid rain.

Groundwater : When rain falls on the ground, some water penetrate the soil and accumulate on the non-porous rocky layer. This is called underground water and the level of water is called water table.
Sometimes the groundwater may come out at the surface to form a natural spring. It may also form a lake.
Groundwater passes through several layers of sand and rocks. It gets filtered through these layers and is free from suspended impurities. However, it may be contaminated with germs and some dissolved salts of calcium and magnesium.
We can obtain groundwater by digging wells and tube

Surface water : Rainwater that runs off the surface of earth to form streams, lakes and rivers is called surface water. Snow melts and the water flows down
to rivers and lakes. Surface water is highly contaminated with germs, suspended impurities and dissolved salts. Sewage water from houses and industries are also discharged into rivers. River water needs to be cleaned before being supplied to cities and towns for drinking. If uncleaned water is consumed, it may cause dangerous diseases like jaundice, cholera and typhoid.

Sea Water
Rivers and streams finally flow into sea and so they are the largest reservoirs of natural water. Sea water is the most impure water. It contains dissolved common salt. Due to this sea water is salty and is called saline water. It is unfit for drinking, cannot be used in irrigation and in industries. People must use water judiciously otherwise there will be a severe water crisis.

Disadvantage of no rainfall at all : Rain is the main source of water. Less or no rainfall can convert an area into a desert. If there is no rainfall for a long period, in continuation, it may lead to drought. There will be no crop, no food for humans and animals. There will be loss of life. An economic crisis will occur in the region and this will become a natural calamity.

Problem due to heavy rain : If there is heavy rainfall, then also problem will rise. The fields will get flooded and crops will be damaged. Again there will be shortage of food and fodder. Collection of rain water will also disrupt the normal life of peoples. Many roads and bridges will get damaged and there will be loss to life and property. Low lying areas will be flooded and people have to be shifted.

Factors affecting shortage of water
(i) Increase in population has increased the demand for water.
(ii) Change in lifestyle of people has increased the consumption of water.
(iii) Urbanisation has decreased the groundwater reserves as concrete roads do not allow seepage of water.
(iv) Industrial demand for water is increasing many times.

Conservation of water : In summers people face shortage of water because the level of groundwater goes down and so there is no water in wells and tube wells. If there is low rainfall the situation becomes even more grim. There is scarcity of drinking water. Therefore, management of water resources is very important and in this water conservation plays an important role

Measures for conservation of water
1. Development of watershed plan for drinking, irrigation and industrial areas.
2. Carrying out surveys to identify over exploited areas.
3. Artificial recharging of ground water.
4. Adoption of flood control methods.
5. Transfer of excess water to deficit areas by interlinking of rivers.
6. Adopting water harvesting methods.
7. Avoiding misuse of water.
8. Organising people awareness programmes.

Rain water Harvesting : Rain water simply flows into drains and is lost.
Instead this rain water can be collected and used later. This is called harvesting of rain water.
Rain water from roof tops and kitchen weather can be collected in underground tanks. Water from these tanks percolate underground and recharge the aquifers.

Preventing water pollution : We can also conserve water by protecting the water bodies from pollution. We should not dump garbage and harmful chemicals from factor in water bodies. Dirty water is bad for marine line. Even plants and animals die around polluted water. If humans consume polluted water they may suffer from many diseases.

Keywords
• Condensation : Process by which water vapour in air changes into liquid water.
• Evaporation : Process by which liquid water turns into vapour.
• Transpiration : Process by which plants lose water in the form of water vapour into the atmosphere.
• Water cycle : The cyclic movement of water from the atmosphere to the Earth and back to the atmosphere through various processes is called water cycle.
• Drought : Abnormally long period of insufficient or no rainfall is called drought.
• Famine : Lack of food in a region for a long period is called famine.
• Rain water harvesting : The process of collecting and storing rainwater from roofs or a surface catchment is called rainwater harvesting

Match the Column

DIRECTIONS : Match Column-I with Column-II and select the correct answer using the codes given below the columns.

Question.
Column-I                              Column-II
(A) Ground water           (p) Excess rains
(B) Ocean                      (q) Aquifiers
(C) Clouds                     (r) Water containing dissolved salts
(D) Floods                     (s) Water vapour and dirt
(a) A → (p); B → (q); C → (r); D → (s)
(b) A → (q); B → (r); C → (s); D → (p)
(c) A → (r); B → (s); C → (p); D → (q)
(d) A → (s); B → (p); C → (q); D → (r)
Answer : B

Question.
Column-I                        Column-II
(A) Drought                (p) Slow process
(B) Surface water       (q) Rivers, ponds etc.
(C) Evaporation          (r) Loss of water by plants
(D) Transpiration        (s) Absence of rains for a long time
(a) A → (s); B → (q); C → (p); D → (r)
(b) A → (s); B → (r); C → (q); D → (p)
(c) A → (s); B → (p); C → (q); D → (r)
(d) A → (p); B → (s); C → (r); D → (q)
Answer : A

Question.
Column-I                                                       Column-II
(A) Water cycle                                 (p) Solid state of water
(B) Hail, snow                                   (q) Condensation
(C) Water vapour changes to           (r) Circulation of water between ocean liquid water and land
(D) Water enters air                         (s) Transpiration
(a) A → (p); B → (q); C → (r); D → (s)
(b) A → (q); B → (r); C → (s); D → (p)
(c) A → (r); B → (p); C → (q); D → (s)
(d) A → (s); B → (q); C → (p); D → (r)
Answer : C

Passage Based Questions

DIRECTIONS : Read the passage (s) given below and answer the questions that follow.

Passage-1
Apart from drinking, there are so many activities for which we use water.
Most of the water is in oceans and seas.
We draw drinking water from taps which is further drawn from a well or a lake etc.

Question. We need water for which of the following?
(a) Baking
(b) Brushing
(c) Cooking
(d) All of these
Answer : D

Question. We need water for
(a) industries
(b) producing many things
(c) Both the above
(d) None of these
Answer : C

Question. Choose the correct option?
(a) All of us (i.e., Indians) get drinking water from taps.
(b) The water that we get from taps is also drawn from a lake, or a river or a well.
(c) Both the above
(d) None of these
Answer : B

Passage-2
If we put some water in a plate and allow the plate to lie in open in sunlight we find that the water from the plate disappears.
Moreover even if we keep the plate in shade the water still disappears.

Question. The process by which the water disappears from the plate is
(a) Evaporation
(b) Condensation
(c) Transpiration
(d) Precipitation
Answer : A

Question. The process of disappearance of water from the plate occurs
(a) rapidly in sunlight
(b) rapidly in shade
(c) with same speed in day and night
(d) occurs only in day time
Answer : A

Question. If we take sea water in plate and allow it to stand in sunlight till whole of the water disappears, we find that
(a) nothing is left in the plate
(b) some solid is left behind
(c) some liquid is left behind
(d) None of the above is correct
Answer : B

Passage-3

Only a small fraction of water available on the earth is fit for use of plants, animals and humans. The total amount of water on earth remains the same, but the water available for use is very limited and is decreasing with over usage.

Question. Why is the demand for water increasing day by day?
(a) The quantity of water used per person is increasing day by day
(b) The number of persons using water is increasing
(c) More and more water is being used by industries
(d) Only (b) and (c) are correct
Answer : D

Question. We have a lot of water in oceans, then how is it said that the amount of usable water is limited?
(a) Sea water is not fit for all our uses
(b) Sea water can not be used directly by us for drinking
(c) Sea water can not be used directly for plant production
(d) All of the above
Answer : D

Question. How is it that total amount of water on earth remains same though it is consumed by us for various activities on a large scale?
(a) Because of water cycle
(b) Because of transpiration
(c) Because of condensation
(d) Because of water harvesting
Answer : A

Assertion/ Reason Based Questions

DIRECTIONS : The questions in this segment consists of two statements, one labelled as “assertion A” and the other labelled as “reason R”. You are to examine these two statements carefully and decide if the assertion A and reason R are individually true and if so, whether the reason is a correct explanation of the assertion. Select your answers to these items using codes given below.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.

Question. Assertion (A) : The sea water is saline.
Reason (R) : The sea water contains many dissolved salts.
Answer : A

Question. Assertion (A) : Role of oceans in supplying usable water is quite important.
Reason (R) : When the sea water reaches us, in various other forms of sources of water, it is no more saline.
Answer : B

Question. Assertion (A) : Sea water changes to water vapours by the process of transpiration in the presence of sunlight.
Reason (R) : When sea water changes into water vapour it leaves the dissolved salts behind.
Answer : D

Question. Assertion (A) : In such areas where there is no vegetation the rain water flows quickly and has no effect on the top layer of soil of that area.
Reason (R) : When water level rises in rivers, ponds etc. Due to excessive rains it causes floods.
Answer : D

Question. Assertion (A) : During drought there is a shortage of food and fodder.
Reason (R) : Droughts result in conservation of water.
Answer : C

Question. Assertion A : Level of ground water below the surface of Earth at a given place is known as water table.
Reason R : Excess use of groundwater in cities is resulting in lowering of water table.
Answer : B

Figure Based Questions

Question. Identify the process represented by the part ‘A’ of the diagram.

(a) Evaporation
(b) Transpiration
(c) Condensation
(d) None of these
Answer : C

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 _____________,

8.The release of water vapour into air by the leaves of plants is called ___________________.

9_______________________ are made of droplets of water, ice crystals, particles of dust and air.

10.Any natural phenomenon which repeats itself after some time is said to constitute _________________________.

11. Continued absence of rain causes _________________________.

12. Drought and floods are called _________________________.

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.

9.The process by which water changes into water vapour on heating.

10. The process by which water vapour change into liquid water on cooling.

11. The falling of drops of water from the clouds.

12. The journey of water from the oceans to the atmosphere and back to the oceans again.

13. Two methods of rainwater harvesting.

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.

8. The water cycle is powered by the heat of the sun and the force of gravity.

9. The main reason of precipitation is that clouds cool off.

IV. Define the following:

Water cycle Rainwater harvesting Precipitation

V. Distinguish between: Evaporation and condensation.

VI . Draw, colour and label the water cycle.

Please refer to attached file for CBSE Class 6 Science Practice Worksheets (20)-Water