Nearly two thirds of the Earth's surface is covered by water. Water exists in liquid, solid, and vapor forms and can easily change between these states. The melting point of ice is the temperature at which ice changes to water. While about 97% of water on Earth is in the oceans, only around 2% is fresh water suitable for human use, so it is important to conserve this precious resource. Water scarcity is a problem in many areas due to factors like pollution, leakage, and waste.

3. INTRODUCTION
Nearly two thirds of the earth’s surface is covered by water.Besides
this surface water, there is underground water and atmospheric water.
The major constituent of all living things is water.Nearly 98% of water
on earth is in the sea.

4. The water which is suited for our use is only two
percent. water is the most common fluid in nature.Unlike
other substances
in nature water exists in the form of liquid,solid and
vapour. water can
easily change from one form to another.

8. Boiling point and melting
point of water
Take some water in a test tube.Insert a thermometer into it.
Note the temperature.Find out the temperature of ice using a
thermometer.Note whether thee is any change in the mercury
level till the ice is completely changed to water.What is the
temperature a which the ice melts?It is the melting point of ice.

12. You know that the sources of water on earth.
Look at the table below
00.282Others10
00.001Rivers9.
00.001Atmosphere8.
00.005Water content in soil7.
00.007Marine water lakes6.
00.009Fresh water lakes5.
00.015Glaciers4.
00.580Underground water3.
02.100Ice mountain2.
97.000Sea water1.
PercentageSourcesSl.No

13. What percentage of total water is suitable for drinking?
Do you realise how important is it to conserve drinking
water?You know that there is scarcity of drinking water
in many parts of our state.What is the reason?Find out.
Is there scarcity of drinking water in your locality?
Study the measures taken by your panchayath to solve it.

14. The amount of water we waste is almost the same as the
water we use.The main reasons of shortage of water are
unplanned irrigation,wasting and pollution.10% of water is
lost by leakage and flaws in water supply.We can reuse a
major part of the water we waste.Scarcity of water can also
be solved to a certain extend by purifying the polluted sources
of drinking water.
How can you purify the polluted water?
The methods used for purification vary from place to place.
Let us examine some common procedures.

15. 1.Screening - Solid impurities are removed in
this stage.Waste water is passed
through wire net and large sized impurities are
removed.

16. 2.Storage - Filtered water is allowed to
remain in the reservoir for a long time.As a
result major part of the impurities settle
down.Ultra violet rays of the sun destroy the
germs in the water.
3.Aeration -The oxygen content of
impure water is kept steady in this stage.The
water in the reservoir is allowed to come in to
contact with air by spraying it into another tank.

17. 4.Filteration - Water is filterated by
passing through sand and gravel.
5.Sterilisation -Chlorine is passed
through the water to kill the bacteria that may
still be present in the water.Water is now
purified and can be used again.

19. Water scarcity cannot be solved by the purification of
polluted water alone.The quantity of water available to
us is declining year after year.We have to find out more
and more sources of drinking water.We have to turn to
another sources also. What measures can be suggested
for this?Discuss.

20. Do you know water is more precious than any other substance.
We see every day so many advertisements,news,documentaries
and pictures through media’s about the conservation of water.
Haven’t you heard about the agitations for drinking water.
In summer it is a very familiar sight to see that people waiting for hours
and travel long distances for a pot of water. What is the other side of it……
We are also familiar with the sight of water flowing like
Stream from damaged pipes on way side.Do you know how much water is
Thus wasted through sheer ignorance and calourness.

21. Can you guess how much water you waste daily?
What are your needs with water? Note down.
For bathing
For drinking
For washing hands and legs