Question

In which case change in entropy is negative.
1.evaporation of water
2.expansion of a gas at constant temperature.
3.sublimation of solid to gas.
4. 2H-- H2

Answer 1

entropy is negative due toevaporation of water

Answer 2

Question: In which case change in entropy is negative?

1. Evaporation of water
2. Expansion of a gas at constant  temperature
3. Sublimation of solid to gas
4. 2h(g) → H2(g)

Solution: $H_2O(l)$ ⇄ $H_2O(v),$ ∆ 0∠S

Expansion of gas at constant temperature, ∆ 0∠S.

Sublimation of solid to gas, ∆ 0∠S

2H(g) → H2(g), ∆ 0∠S (∴ ∆ Ng ∠ 0)