Question

In which of the following changes, entropy decreases?

• A. Rusting of iron
• B. Melting of ice
• C. Vaporisation of camphor
• D. Crystallisation of sucrose from solution

Hint:

In crystallisation, when a solute forms a crystal, the system becomes more ordered, which leads to a decrease in entropy.

Answer 1

The Correct Option is D

Entropy is a measure of the disorder or randomness of a system. In the case of crystallisation of sucrose from solution, the molecules of sucrose become more ordered as they form a crystal lattice, which leads to a decrease in entropy. - Rusting of iron increases disorder as new compounds are formed.
- Melting of ice involves a transition from a solid to a liquid, which increases entropy.
- Vaporisation of camphor also increases entropy as a solid turns into a gas. Thus, crystallisation of sucrose from solution is the process where entropy decreases.