Page 142 - Genius Kidz Prudence Learning Sc-8

emitting pollutants at an alarming level. The beside the monument. However, the
city roads are so congested that for a 15 foundations of the building are made of wood
minutes drive, one has to spend an hour thus which must be kept moist to avoid subsidence.

consuming more fuel and emitting more In addition the water is heavily polluted
pollutants." because of the discharges from factories and
With a greater population, there is more from human waste. This clogs up drains around
demand for water which has meant that the the building.
water table is dropping in the river which runs

! Pollution can be defined as any undesirable change in the physical, chemical or biological properties
of air, water or land.
! Pollution is mainly of 3 types - air, water and land or soil pollution.

! Photochemical smog is the smog formed due to the action of sunlight on hydrocarbons and
nitrogen oxides.
! Rain carrying sulphuric acid and nitric acid is called the acid rain.
! Ozone is the protective umbrella of earth crust as it blocks harmful UV radiation from reaching the
earth.
! Air polluants like CFC’s, oxygen, nitrogen oxides and hydroxy radicals are depleting stratospheric
ozone.

! There are two sources of water pollution - point sources and man-made sources.
! Causes of water pollution include-domestic wastes, industrial wastes and radioactive wastes.

EXERCISE
EXERCISE

1. Multiple choice questions.
(a) Ozone is an example of :

(i) greenhouse gas (ii) water pollutant
(iii) both (i) and (ii) (iv) None of these

(b) Vegetable peels thrown off on the ground cause :
(i) land pollution (ii) air pollution (iii) water pollution (iv) noise pollution
(c) Explosives are an example of :

(i) biodegradable pollutant (ii) non-biodegradable pollutant
(iii) natural pollutant (iv) both (ii) and (iii)

(d) Carboxy haemoglobin is formed by:
(i) carbon monoxide (ii) carbon dioxide (iii) sulphur dioxide (iv) nitrogen oxide.
(e) Smog is:

(i) smoke (ii) smoke + fog (iii) fog (iv) (NO)

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