Revision: Water Science SSLC (English Medium) Class 8 Tamil Nadu Board of Secondary Education

Eutrophication: “Organic matter in sewage poured into water bodies generally results in excessive growth of algae – which deoxygenates water and produces deadening atmosphere there.”

The amount of heat energy required by ice to change into water is called the latent heat of fusion of ice.

The temperature at which a liquid turns into solid when cooled is known as the freezing point. The freezing point of water is 0°C.

The temperature at which water boils and changes to steam is called as boiling point. The boiling point of water is 100°C at atmospheric pressure.

The water suitable for drinking is called potable water.

The water present in different natural sources has different substances dissolved in it. The water drawn from certain sources forms a lather with soap rather easily. Such water is called soft water.

Water obtained from various sources does not easily form a lather with soap, rather it forms a white sticky scum or a precipitate. This water is called hard water.

Oil spills are the accidental discharges of petroleum into oceans or estuaries. The sources of spills are overturned oil tankers, offshore oil mining, and oil refineries.

Water pollution means any change in the water quality which makes it unsuitable for use by humans and by other living organisms.

The amount of heat that is needed to raise the temperature of a unit mass of a substance by 1°C is called specific heat capacity.