For a pure substance at the same temperature, which phase has the highest entropy?

• A. All phases have the same entropy at the same temperature
• B. Solid
• C. Liquid
• D. Gas

Answer: (D)

Verified step by step guidance

1. Understand that entropy is a measure of the disorder or randomness in a system. The more disordered the particles are, the higher the entropy.
2. Recall the three common phases of matter: solid, liquid, and gas. In solids, particles are tightly packed in an ordered structure, so entropy is low.
3. In liquids, particles are less ordered than in solids and can move around more freely, so entropy is higher than in solids.
4. In gases, particles move independently and occupy a much larger volume with high randomness, resulting in the highest entropy among the three phases.
5. Therefore, at the same temperature, the phase with the highest entropy is the gas phase.