Question

In which case change in entropy is negative ?

• A. Sublimation of solid to gas
• B. $2H(g) \rightarrow H_2(g)$
• C. Evaporation of water
• D. Expansion ofa gas at constant temperature

Answer 1

Answer: (B)

- $H _2 P (\ell) \rightleftharpoons H _2 O ( v ), \Delta S >0$
- Expansion of gas at constant temperature, $\Delta S >0$
- Sublimation of solid to gas, $\Delta S>0$
- $2 H ( g ) \longrightarrow H _2( g ), \Delta S <0(\because \Delta ng <0)$