Why is air considered as a mixture?

Air contains oxygen and nitrogen as its major constituents of air. These gases retain their properties in the air. Hence, air is considered a mixture.

[Extra information:

Mixtures consist of two or more different kinds of particles or two or more pure substances mixed together, but these are not chemically bound.

Example: Sugar solution is a mixture because it can be separated into its constituents by physical processes (like evaporation). It shows the properties of both sugar and water.

The Earth's atmosphere is made up of a mixture of gases called "air." These are colorless and odorless gases. It is made up of 78 % nitrogen, 21% oxygen, and 1 % other gases and water vapour. It also contains trace amounts of carbon dioxide, neon, helium, methane, krypton, hydrogen, nitrous oxide, xenon, ozone, iodine, carbon monoxide, water vapours, and ammonia.]