In which of the following processes entropy increases? Choose the correct answer from the options given below:
- A and C
- A, B and D
- A, C and D
- C and D
Answer
(3) A, C and D
Solution
A. Liquid → vapour: molecules become much more disordered → S > 0.
B. Cooling a crystalline solid from 130 K to 0 K: thermal motion decreases (S → 0 at 0 K) → S < 0.
C. A solid gives gases ( ng = +2) → S > 0.
D. One mole of gas gives two moles of gas ( ng = +1) → S > 0.
Entropy increases in A, C and D.
Answer: (3)