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Percentage composition of air.

Answer Text:
AIR AND COMBUSTION
Introduction:
- Air is a gaseous mixture constituted of several gases, water vapour and pollutants.
Combustion:
- Is the burning of substances, usually in presence of air // oxygen;
- During combustion only the oxygen component of air is used; .e the active part of air.
Percentage composition of air.

Note:
- From the noble gases argon is the most abundant, constituting about 0.93% of the entire 1% Oxygen and combustion.
- When substances burn in air they consume oxygen.
- Thus the process of combustion utilizes mainlyoxygen;
- The reactions in combustion are normally exothermic (give out heat) and often involve flame.
Note:
Combustion in which a flame is used is called burning;
- In combustion if all the oxygen in a given volume of air is used, the final volume of air reduces by about 21.0%;
- Since oxygen is the only constituent of air participating in combustion its termed the active part of air.