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

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

Copper oxide (CuO) is formed by the chemical reaction between copper (Cu) and oxygen (O). The copper and oxygen atoms are chemically bonded in a fixed ratio, resulting in a new substance with properties distinct from either copper or oxygen.

Key Points:

* Copper oxide has a specific chemical formula (CuO).

* The properties of copper oxide are different from the properties of copper and oxygen.

* Copper oxide cannot be separated into copper and oxygen by physical means; you need a chemical reaction.