Concept:Entropy is a measure of disorder or randomness in a system.
Explanation:During phase changes, entropy increases when the substance becomes less ordered.
The general order of entropy is: solid
< liquid
< gas.
This means the highest entropy increase occurs when changing from liquid to gas.
Gas particles move freely, spread out, and occupy a much larger volume than liquid particles.
This dramatic increase in molecular disorder produces a large positive entropy change,
ΔS.
The other transitions involve smaller increases or actual decreases in entropy.
Answer:A. Liquid → Gas