Page 197 - Chemistry ICSE Class IX

Atmospheric Pollution 185
Examples: Carbon monoxide (CO), Sulphur dioxide (SO ),
2
Hydrocarbons (HC).
ƒ Secondary pollutants. The pollutants which are formed by chemical
reactions between the primary pollutants amongst themselves or with
the atmospheric gases are called secondary pollutants.
Examples: Sulphuric acid (H SO ), Nitric acid (HNO ) and
4
3
2
Peroxyacetyl nitrate (PAN, CH CO . OO . NO ), Chemical smog.
3
2
ƒ Solid pollutants. The pollutants which exist in the solid form are
called solid pollutants.
Examples: Mining waste, Agricultural waste, Flyash, Smoke particles,
wastes from food processing industry, paper industry etc.
ƒ Liquid pollutants. The pollutants which occur as liquid are called
liquid pollutants.
Examples: Sewage, waste water from laundries, kitchen and chemical Agricultural waste
industries, Agricultural run-off containing fertilisers, pesticides,
insecticides etc.
ƒ Gaseous propellants. Poisonous and toxic gases or vapours are called
gaseous propellants.
Examples: Gaseous wastes from industries containing oxides
of carbon, sulphur, nitrogen etc., ammonia, hydrogen sulphide,
chloro uorocarbons and hydrocarbons.
Š Gaseous pollutants are also called air pollutants.
Š Gaseous pollutants soluble in water cause water pollution.

ASSIGNMENT 1

Environment, Environment pollution, Type of environmental pollution, Types of pollutants.

ϭ͘ EĂŵĞ ƚŚĞ ƚŚƌĞĞ ĐŽŵƉŽŶĞŶƚƐ ŽĨ ŽƵƌ ĞŶǀŝƌŽŶŵĞŶƚ͘
Ϯ͘ ĞĮŶĞ ƚŚĞ ĨŽůůŽǁŝŶŐ͗ ;ĂͿ ƉŽůůƵƚĂŶƚ͕ ;ďͿ ƉŽůůƵƟŽŶ ƉƌŽĐĞƐƐ
ϯ͘ EĂŵĞ ŽŶĞ ƉŽůůƵƚĂŶƚ ŽĨ ĞĂĐŚ ƚLJƉĞ͗ ;ĂͿ ^ŽůŝĚ ƉŽůůƵƚĂŶƚ͕ ;ďͿ >ŝƋƵŝĚ ƉŽůůƵƚĂŶƚ ĂŶĚ ;ĐͿ 'ĂƐĞŽƵƐ ƉŽůůƵƚĂŶƚ
ϰ͘ EĂŵĞ ƚǁŽ ĞĂĐŚ ŽĨ ƚŚĞ ƉƌŝŵĂƌLJ ĂŶĚ ƐĞĐŽŶĚĂƌLJ ƉŽůůƵƚĂŶƚƐ͘

The Atmosphere

What is meant by the atmosphere
/Ŷ ƚŚĞ ƚƌŽƉŽƐƉŚĞƌĞ͕ ƚŚĞ ĂǀĞƌĂŐĞ
The cover of the air surrounding the earth is called atmosphere. Atmosphere ƚĞŵƉĞƌĂƚƵƌĞ ĚĞĐƌĞĂƐĞƐ ďLJ ĂďŽƵƚ ϲΣ
extends from the earth’s surface to about 1000 km. But about 99% of the ĨŽƌ ĞǀĞƌLJ ŽŶĞ ŬŝůŽŵĞƚƌĞ ŽĨ ĂůƟƚƵĚĞ͘
atmospheric air is present within 40 km from the earth’s surface.
The main layers of the atmosphere, from the surface of the earth
upwards are shown in the picture given alongside and described below:
ƒ Troposphere. Most of the atmospheric air is present in troposphere.
Thickness of the troposphere changes from about 8 km over the poles
to about 18 km over the equator. Clouds, rain and snow are seen in
troposphere.
ƒ Stratosphere. The layer of atmosphere above troposphere up to a
height of about 50 km is called stratosphere. In stratosphere, there
is very little water vapour. Ozone layer lies in the central zone of
stratosphere.
ƒ Mesosphere. Mesosphere extends from the height of 50 km to 80 km.
In the mesosphere, air is very thin and the temperature falls to about
–85°C at a height of about 80 km from the earth. The layers of the atmosphere