* Mixture: A mixture is a combination of two or more substances that are not chemically bonded. The substances in a mixture can be separated by physical means (like filtration or evaporation).

* Compound: A compound is formed when two or more elements chemically combine in a fixed ratio. The resulting compound has properties different from the original elements.

Copper sulfate (CuSO₄) is formed by the chemical combination of copper (Cu), sulfur (S), and oxygen (O) in a specific ratio. This chemical bonding creates a new substance with its own unique properties, distinct from the original elements.

Therefore, pure copper sulfate is a compound, not a mixture.