Question

Most substance ___________ on heating and ________ on cooling.

• A. Expand
• B. Contract

Answer 1

1. Heating, the molecules in the substance gain momentum. This causes molecules to move further apart, causing the substance expands.
2. There are three types of expansion: Linear, Superficial and Volume.
3. The reverse of this is observed during cooling.
4. During cooling, the molecules in the substance slow down and this causes the molecules to come closer to each other thus the substance contracts.

Hence, most substances expand on heating and contract on cooling.