When two pure substances are combined so that each retains its own properties, the result is a mixture.

Here's why:

* Mixtures are formed when two or more substances are physically combined but not chemically bonded. This means the substances retain their individual properties and can be separated by physical means.

* Compounds, on the other hand, are formed when two or more substances chemically combine to create a new substance with entirely different properties.

Examples of Mixtures:

* Salt and pepper: You can easily see the individual grains of salt and pepper.

* Sand and water: The sand settles to the bottom, and the water remains liquid.

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

Let me know if you have any other questions!