* Mixture: A combination of two or more substances where each substance retains its individual properties.

* Compound: A substance formed when two or more elements chemically combine in a fixed ratio.

In this case, you have oxygen gas (O₂) and nitrogen gas (N₂). They are both elements, and they are not chemically bonded together. They are simply mixed together.

Key points:

* The gases can be separated by physical means (like distillation).

* The ratio of oxygen to nitrogen can vary.

* The properties of oxygen and nitrogen remain unchanged in the mixture.