Page 2 - COMPOSITION AND PROPERTIES OF AIR

 It contains 78% nitrogen and 21% oxygen. The remaining 1% consists of
water vapour and gases such as argon, helium, neon and carbon dioxide.

 Different gases present in the air :

1. OXYGEN:

 It is essential for the survival of living organisms.
 It is the oxygen in the air that helps humans and animals carry out the

breathing process.
 Oxygen is also required for fire to keep burning. If we were to keep an
inverted tumbler covering a burning candle, the candle will go off in a
few seconds because of the lack of oxygen-containing air due to the
tumbler. On the other hand, the candle in the open continues to burn as

it receives oxygen in sufficient amount from the air around it.
 Air contains about 21% of oxygen.

2. NITROGEN:

 Dry air is said to contain about 78% of nitrogen. This component of air
helps plants in their growth process as it is an essential nutrient for
plants.
 Plants do not use the nitrogen present in the air directly. Certain types
of bacteria present in the soil convert nitrogen into different forms that

can be used by the plants.
 When animals consume plants, they obtain nitrogen along with other
nutrients from them.