* Compound: A compound is formed when two or more elements chemically combine in a fixed ratio. For example, water (H₂O) is a compound made of hydrogen and oxygen.

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

Rain is a mixture because:

* It's primarily water (H₂O), but it also contains dissolved gases, minerals, and even pollutants.

* These components aren't chemically bonded together. They can be separated through processes like evaporation or distillation.

Think of it this way: If you boil a pot of water, the water will evaporate, leaving behind any dissolved minerals or impurities. This shows that the components of rain are not chemically bound together.