In which of the following physical states does a given substance have the highest entropy?

A. solid
B. gas
C. liquid
D. all of the above

would this be A?

no. A has the least.

Gas

To determine in which physical state a substance has the highest entropy, we need to understand the concept of entropy. Entropy is a measure of disorder or randomness in a system.

In general, the higher the number of possible arrangements or states a system can have, the higher its entropy. So, a substance will have the highest entropy when it has the greatest number of possible arrangements or states.

In the case of the given options, let's consider each physical state:

A. Solid: In a solid state, molecules are arranged in an ordered, compact structure with little freedom of movement. The particles are closely packed in a regular pattern, and there are limited possible arrangements. Therefore, the entropy of a substance is generally lower in the solid state compared to other states.

B. Gas: In a gas state, molecules are in a highly disordered and random arrangement. Gas particles have more freedom of movement and can occupy a larger space. They are not confined to a fixed shape or volume and can move around freely. Due to this high degree of randomness and a greater number of possible arrangements, the entropy of a substance is generally higher in the gas state.

C. Liquid: In a liquid state, molecules are more ordered and closer together compared to gases, but they have more freedom of movement compared to solids. While liquids have more disorder than solids, they still have fewer possible arrangements compared to gases. Therefore, the entropy of a substance is generally higher in the liquid state compared to the solid state but lower compared to the gas state.

D. All of the above: Since we have determined that the entropy is generally highest in the gas state, the correct answer would be B, not D. Gas is the physical state where a substance tends to have the highest entropy due to the greater number of possible arrangements and higher degree of disorder.

So, the correct answer is B - gas.