* Chemical Property: A chemical property describes how a substance reacts with other substances. It involves a change in the substance's chemical composition.

* Rusting: Rusting is a chemical reaction between iron, oxygen, and water. This reaction forms iron oxide (rust), which is a different substance with different properties than the original iron.

In contrast, a physical property can be observed without changing the substance's chemical composition. Examples of physical properties include color, density, and melting point.

Therefore, the ability to rust is a chemical property because it describes how iron reacts with other substances to form a new compound (rust).