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Unit-III : Nature Around Us
10 Air and Water
l Air and its composition
l Atmosphere
l Layers of Air
Inside
Inside
the l Properties of air
the
Chapter
Chapter l Utility of Air Pressure
l Water : removing insoluble and soluble impurities
l Sedimentation, Filtration, Decantation, Chlorination.
l Water supply to our homes
AIR
All living thing needs air to breathe. Animals and plants would die without it.
Air also holds aeroplanes and kites in the air and is used to inflate tyres,
balloons, footballs etc.
Composition of AirComposition of AirComposition of Air
Air is a mixture of gases. Nitrogen and
oxygen are the main gases found in air. Oxygen
20.9% Argon Gases
Oxygen is used for respiration and for 0.90%
burning. Nitrogen
78% Other gases
Nitrogen is not required for burning but is 0.17%
consumed by plants to make their food. Carbon dioxide
0.03%
In addition to nitrogen and
oxygen, air consists of small
amounts of some other gases
including argon, carbon dioxide,
neon, helium and methane.
Besides gases, air also contains
water vapours, dust, pollens and
bacteria. The water vapour in air is
the source of rain and snow.
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