Air is a mixture because of the following
- Air does not have a fixed composition.
The composition of air varies from
place to place.
- Artificial air can be made by mixing
the various components of air in the
same proportions in which they occur
at a place, and when this is done, no
energy changes are noticed.
- The components of air can be separated
by a physical method such as fractional
distillation of liquid air.
- Liquid air does not have a definite
boiling point. It boils over a range of
temperature between -196ºC and
- If air is a compound, the composition
of air expelled from humans should not
be different from the composition of air
around us. But it is known that during
respiration, the exhaled air has lower
percentage of oxygen than the ordinary