Question

Identify the correct statement regarding entropy.
(a) At absolute zero temperature, entropy of a
perfectly crystalline substance is taken to
be zero.
(b) At absolute zero temperature, the entropy
of a perfectly crystalline substance is
positive.
(c) Absolute entropy of a substance cannot
be determined.
(d) At 0°C, the entropy of a perfectly crystalline
substance is taken to be zero

Answer 1

The entropy of a perfect crystal at absolute zero is exactly equal to zero

option A

Answer 2

The correct statement is (a) At absolute zero temperature, entropy of a  perfectly crystalline substance is taken to  be zero.

Explanation:

• The third law of thermodynamics talks about the property of a closed system in thermodynamic.
• The perfect crystalline structure (with no linear or point of planar imperfections) to give the formula of third law of thermodynamics.
• According to this law, the entropy of the system becomes constant when the absolute temperature of the system approaches zero.
• Thus, when the absolute temperature is zero, the entropy of perfectly crystalline substance is taken as zero.