According to chemistry, which of the following is an example of a physical change?
- ARusting of iron
- BBoiling of water
- CBurning of wood
- DFormation of a green layer on copper utensils
- ENone of the above/More than one of the above
Show answer and explanation
Correct answer: (b) Boiling of water
Explanation
Boiling water only changes liquid water into steam; the substance is still H₂O, and cooling turns it back into water. So it is a physical change.
Rusting (hydrated iron oxide), burning wood (CO₂, water and ash) and the green layer on copper (basic copper carbonate) all form new substances: they are chemical changes.