Entropy is best described as a measure of
- A. the total heat in a system
- B. the disorder of a system
- C. the temperature of a system
- D. the pressure of a system
Explanation
A system with many possible microscopic arrangements has high entropy, so melting ice or letting a gas expand into a vacuum both increase it. The second law says the entropy of an isolated system never decreases, which is what gives time its direction. Local decreases are possible, as when water freezes, but only at the cost of a larger increase elsewhere.