For a pure substance at the same temperature and pressure, which state of matter generally has the greatest entropy?

• A. Gas
• B. Plasma
• C. Solid
• D. Liquid

Answer: (A)

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 general order of entropy for the three common states of matter at the same temperature and pressure: solid < liquid < gas. This is because particles in solids are tightly packed and have limited movement, while particles in liquids have more freedom to move, and particles in gases move freely and occupy more volume.
3. Consider plasma as an ionized gas with even more energetic particles, but since the problem focuses on common states and typical conditions, plasma is usually not considered in basic entropy comparisons.
4. Conclude that among solid, liquid, and gas, the gas phase has the greatest entropy due to the highest degree of molecular freedom and disorder.
5. Therefore, the state of matter with the greatest entropy at the same temperature and pressure is the gas phase.