Is air a mixture or a compound? Give three reasons.
Air is a mixture and not a compound as discussed below: (i) The properties of a mixture are in between those of its constituents. The two major components of air are oxygen (20.9% by volume) and nitrogen (78.1% by volume). In oxygen, any fuel bums brightly but in nitrogen it gets extinguished. In contrast, in air the fuel bums slowly. (ii) The components of a mixture can be separated by simple physical methods. For example, the components of air can be separated by fractional distillation of liquid air. (iii) The composition of a mixture is variable. The composition of air is also variable. It has more oxygen in the country side than in big cities. (iv) When air is obtained by mixing its constituent gases, no heat is either evolved or absorbed. (v) Liquid air does not have a fixed boiling point.
