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

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

In a potassium iodide solution, potassium iodide (KI) is dissolved in water (H2O).

* Potassium iodide (KI) is a compound, formed by the chemical combination of potassium and iodine.

* Water (H2O) is also a compound.

The solution is formed by the physical process of dissolving KI in water. The KI molecules are surrounded by water molecules, but they don't chemically react to form a new substance. You can separate the potassium iodide from the water through evaporation.

Therefore, a potassium iodide solution is a mixture of the compound potassium iodide and the compound water.