Question

Evaporation of water taking place at $100^\circ\text{C}$ at 1 atm. pressure, the correct choice of change in $\Delta S$ for system and surrounding would be :

• A. $\Delta S_{\text{system}} > 0, \Delta S_{\text{surrounding}} > 0$
• B. $\Delta S_{\text{system}} < 0, \Delta S_{\text{surrounding}} < 0$
• C. $\Delta S_{\text{system}} < 0, \Delta S_{\text{surrounding}} > 0$
• D. $\Delta S_{\text{system}} > 0, \Delta S_{\text{surrounding}} < 0$

Hint:

Whenever an endothermic phase change occurs (like melting or boiling), the system's entropy always increases ($>0$) and the surroundings' entropy always decreases ($<0$). For exothermic phase changes (freezing, condensation), the exact opposite is true.

Answer 1

The Correct Option is D