Why air is a mixture and not a compound?

Answer:

Mixture:

• When two or more substances are mixed without having any chemical change, then the final substance is known as a mixture.
• Its components can be separated easily by physical means.
• For example, a mixture of salt in water.

Compound:

• A pure substance constituted of two or more elements combined chemically in a fixed ratio is called a compound.
• It can be split into these simpler and different substances by chemical means

Air as a mixture:

• Air is nothing but a general name for the mixture of gases like Nitrogen$\left(\mathrm{N}\right)$ mixed with Oxygen$\left(\mathrm{O}\right)$, Water$\left({\mathrm{H}}_2\mathrm{O}\right)$ vapor, Argon$\left(\mathrm{Ar}\right)$, Carbon dioxide$\left({\mathrm{CO}}_2\right)$, and dust.
• These components are not mixed in fixed ratios.
• It means Air is a mixture.

Conclusion:

Therefore, the air is a mixture and not a compound.