Question

Identify the reversible change(s) among the following:
Change 1: Boiling of water
Change 2: Burning of wood
Change 3: Knitting a sweater

Answer 1

Reversible change: It is a change in which the original substance can be re-obtained.
Irreversible change: It is a change in which the original substance cannot be re-obtained.

1. Boiling of water: Produces steam that can be condensed back to liquid water. Hence, it is a reversible change.
2. Burning of wood: Produces ash and smoke. These substances cannot be converted back to wood. Hence, it is an irreversible change.
3. Knitting a sweater: A sweater can be unknitted to get the wool back. Hence, it is a reversible change.