Page 169 - ICSE Chemistry 8

Water is extensively used at home to meet our daily requirements like bathing, cleaning, washing, etc. It
is also required for various agricultural and industrial prac ces. It also helps in genera ng electricity by
rota ng turbines and the electricity so produced is termed as hydroelectricity.

Thirst for Knowledge

• Fruits and vegetables have high water content which helps to meet our daily requirement of water.

• Water has a very high specifi c heat. It means that it can absorb or lose a lot of heat before its temperature
changes. This property is important in maintaining body heat in mammals.

Uses of Water

• A large amount of water is needed by plants during photosynthesis.
• Water also helps in transporta on of minerals in various parts of the plants.
• It is used as a coolant in power genera on from fossil fuels and also in car radiators.
• Water is used for transporta on and sanita on purposes.

• Water is needed for many recrea on and sport ac vi es such as swimming, river ra ing, boa ng,
etc.

generating electricity irrigation transportation
Fig. 8.2: Uses of water

Sources of Water

The major sources of water are rainwater, surface water and groundwater.

Rainwater

Rainwater is the purest form of water. As we know, water vapour present in the atmosphere condense to
form clouds and fall as rain. Rainwater is important as it maintains the level of water in the water table.
Due to air pollu on, rainwater gets polluted while falling.
Surface Water

Surface water consists of water present in oceans, seas, rivers, lakes, etc.
• Water present in oceans and seas contains a large amount of dissolved salts. It is saline or salty
water. This water is unfi t for consump on and other uses like washing, irriga on and industrial
purposes.

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