Explanation:
Rusting is a chemical change that involves the oxidation of iron in the presence of oxygen and water, leading to the formation of iron oxide (rust). However, the change in color that occurs during rusting can be attributed to physical changes in the substance. Here's why:

Chemical Change:
- Rusting is a chemical change because it involves the rearrangement of atoms in the iron and oxygen molecules to form iron oxide.
- This process is irreversible and leads to the formation of a new substance with different chemical properties.

Physical Change - Change in Color:
- The change in color during rusting is a physical change because it does not alter the chemical composition of the iron or oxygen molecules.
- The red-brown color of rust is due to the presence of iron oxide, which has a different molecular structure than iron.
- The change in color is a result of light being absorbed and reflected differently by the iron oxide compared to iron, leading to a visible change in color.
- This change in color is a physical property that can be observed without altering the chemical nature of the substance.
In conclusion, while rusting is a chemical change that involves the formation of iron oxide, the change in color that occurs is a physical property resulting from the different molecular structure of iron oxide compared to iron. This distinction highlights the complex nature of chemical and physical changes in matter.