What is the standard entropy of a perfectly crystalline solid substance at absolute zero (), according to the Third Law of Thermodynamics?

Answer and explanation

Correct answer: A.

  1. Step 1: Recall the Third Law of Thermodynamics formulated by Walther Nernst and Max Planck.
  2. Step 2: At absolute zero (), thermal motion ceases and a perfect crystal has only one microstate ().
  3. Step 3: According to Boltzmann's entropy formula .
Answer
.
Why not the others: Negative infinity violates the minimum non-negative property of statistical entropy; represents residual entropy of a disordered two-state system (like ); is an arbitrary non-zero constant.

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