Question

Identify the correct statements regarding entropy

• A. At $0^{o}C,$ the entropy of a perfectly crystalline substance is taken to be zero
• B. At absolute zero of temperature, the entropy of all perfectly crystalline substance is positive
• C. At absolute zero of temperature, the entropy of all crystalline substance is taken to be negative
• D. At absolute zero of temperature, the entropy of a perfectly crystalline substance is taken to be zero

Answer 1

The correct option is D At absolute zero of temperature, the entropy of a perfectly crystalline substance is taken to be zero

According to the third law of thermodynamics :
The entropy of all perfect crystalline substances is zero at T = 0 K (or absolute zero).

As, at T = 0 K, all energy of thermal motion has been quenched, and in a perfect crystal all the atoms or ions are in a regular, uniform array.