(a) When air is contaminated by un wanted substances which have
a harmful effect on both the living and nonliving, it is referred
to as air pollution.
(air pollution, harmful, living, unwanted, non-living,
(b) Many industries are responsible for causing air pollution.
Petroleum refineries are a major source of gaseous pollutants
like sulphur dioxide and nitrogen dioxide.
(sulphur dioxide, refineries, industries, nitrogen dioxide,
gaseous, liquid, people, air).
(c) While brushing your teeth, leaving the tap running may
waste several drops of water.
(tap, litres, brushing, washing, drops)
(d) Water which is suitable for bathing is called soft water.
(washing, bathing, drinking, potable, soft).
(e) Water which looks clean still has disease carrying microorganisms
and dissolved impurities.
(insects, microorganism, particles, dissolved, harmful)