Composition of Air:-
We need air to breath in oxygen gas in our body so that our body may keep on doing its various metabolic activities normally. Thus air is the basic requirement for life on earth. Without air almost all living animals will perish from earth. Air is a mixture of many gases like nitrogen, oxygen, carbon dioxide, carbon monoxide, oxides of many other metals and non-metals, water vapours, noble gas and dust particles.
Approximate composition of Air
Nitrogen 78%
Oxygen 21%
Carbon dioxide 0.03%
All other gases less than 1%
Oxygen gas is the most important constitute of air. It helps us in respiration and producing energy from food by process of oxidation. Oxygen gas also helps in combustion of fuels. We can say that oxygen is a supporter of combustion. To understand role of oxygen gas in combustion watch the following experiment.