Here's why:

* Mixture: A combination of two or more substances where each substance retains its own chemical identity. The components of a mixture can be separated by physical means.

* Compound: A substance formed when two or more elements chemically combine in a fixed ratio. Components of a compound cannot be separated by physical means.

Examples of mixtures:

* Salt and pepper: You can easily separate the salt from the pepper by using a sieve.

* Sand and water: The sand will settle to the bottom, and you can pour off the water.

* Air: A mixture of gases like nitrogen, oxygen, and carbon dioxide.

Let me know if you have more questions about mixtures!