At absolute zero, the entropy of a pure crystal is zero. This is

Explanation

(1) According to third law of thermodynamics, at 0 K, the entropy of a perfectly crystalline substance taken as zero.
(2) The sign of `triangleG` for a reaction that is exothermic `(triangleH" is -ve")` and accompanied by an increase in entropy `(triangleS" is +ve")` will be always negative.