Page 156 - Science Class 07

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Scarcity of Water

• Where did Water Come from? • Water and Living Beings • Availability of Water
• Conserva on of Water • Rain Water Harves ng • Potable Water
• Pollu on of Water • Preven on of Water Pollu on

The water in the bodies is essen al for our life. in short supply for drinking. It is indeed very
Without water, we cannot survive. Since the useful to us in our day-to-day life. We use it for
water in the bodies is con nually being used or drinking, bathing, cleaning, washing, cooking
lost, it needs to be con nually replaced and the and gardening.
best fluid to replace it with is water.
Besides, water is largely used in industry, for
producing electricity, in agriculture and in

thermal plants which are fun by steam power.
And who doesn’t know that steam is the
gaseous form of water.
Apart from it, water is very important for life. It
has nutrients that support life. However, it
helps the internal chemical process going on
Water is the commonest liquid found in nature. inside the bodies of all living things. All these
It covers about 71% of the earth’s surface. It is characteris cs of water clearly prove that it is a
there in oceans, rivers, lakes and ponds. It is wonder liquid.

there inside the earth also as groundwater that WHERE DID WATER COME FROM?
we obtain through wells, hand-pumps and
When the earth was formed out of a super hot
from springs. It is also there in the air in the
cloud, it has certain elements but no oxygen. In
form of vapour and as snow on very high
due course, its heavier elements—iron and
mountains and ice-caps.
nickle—sank inwards due to gravity and formed
Water is one of the basic needs of living beings. its core. As for the lighter elements like silica,
It is the second life-giver a er the air. Though it they moved outwards to form the earth’s crust
is present in plenty on the earth, yet it is always leaving the other material in between as it was

156 Science-7