Answer:
chemical change
Step-by-step explanation:
Rusting of iron is a chemical change which involves oxidation reaction.
Long exposure of iron to water or oxygen causes rusting in iron. In the process iron is oxidized to form ferric oxide or iron (III) oxide.
The balanced chemical reaction of rusting is mentioned as under:
H₂O
4 Fe + 3O₂ → 2 Fe₂O₃
Here, Fe = iron
O₂ = oxygen
H₂O = water
Fe₂O₃ = ferric oxide
In the reaction, iron reacts with oxygen in the presence of water to produce ferric oxide. It is a chemical change because this change is irreversible i.e. once ferric oxide is formed it can not be converted into iron again. Also, the properties of ferric oxide are completely different from those of iron.