Answer: Option (B) is the correct answer.
Explanation:
A physical property is a property in which there occurs no change in chemical composition of the substance.
For example, mass, density, size, hardness, melting and boiling point etc are all physical properties.
A physical property is basically observable in nature.
Whereas a chemical property is the property in which chemical composition of the substance changes.
For example, reactivity, combustibility, toxicity etc are all chemical properties.
So, when iron rusts on exposure to water and oxygen then it forms a layer of oxide on the surface of iron which is a chemical change.
Hence, we can conclude that iron rusts when exposed to water and oxygen is a chemical property of iron.
