6. Rusting of iron is a chemical change.
1. When iron is exposed to air, it gets oxidized by oxygen in air in the presence of moisture to form reddish brown coloured hydrated iron oxide. This process is called rusting of iron. The number of water molecules in the rust varies.
4Fe(s) + 3O2(g) + 2xH2O(l) 2Fe2O3.H2O(s)
Iron Oxygen Water Hydrated iron oxide
2. The chemical properties of iron oxide are different from iron and oxygen.
3. We cannot obtain back iron from rust(iron oxide) by simple method i.e. change is irreversible.
Hence rusting of iron is a chemical change.