Home PYQs UPPSC UPPSC MCQs Prelims 1997 (GS Paper I)

Question

What changes will the volume of water show if the temperature is lowered from 9 °C to 3 °C:

  1. the volume will not change
  2. the volume will first increase and then decrease
  3. the volume will first decrease and than increase
  4. water will freeze

Answer:

Option C: the volume will first decrease and than increase

Detailed Solution:

The correct answer is “the volume will first decrease and than increase”.

The volume will first decrease and than increase. This unique behavior of water is due to its anomalous expansion.

As the temperature decreases from 9°C to 4°C, the water molecules come closer together, and the volume decreases. However, from 4°C to 3°C, the water molecules start to form a crystalline structure (similar to ice), which occupies more space. Thus, the volume increases.