Final answer:
The entropy changes of the systems in these processes are as follows: (a) negative, (b) positive, (c) positive, (d) positive, (e) zero, (f) positive.
Step-by-step explanation:
(a) The entropy change of water vapor that condenses on a cold surface is negative. When water vapor condenses, it goes from a more disordered state (gas) to a more ordered state (liquid), resulting in a decrease in entropy.
(b) The entropy change of gas in a container that leaks into the surrounding atmosphere is positive. When the gas leaks, it spreads out and occupies a larger volume, leading to an increase in entropy.
(c) The entropy change of an ice cube that melts in a glass of lukewarm water is positive. The melting of a solid into a liquid increases the disorder of the system.
(d) The entropy change of the lukewarm water of part (c) is also positive. The increase in entropy is due to the increased molecular motion as the temperature of the water rises.
(e) The entropy change of a real heat engine performing a cycle is zero. In a complete cycle, the entropy change of the system and its surroundings are equal and opposite, resulting in no net change in entropy.
(f) The entropy change of food cooled in a refrigerator is positive. Cooling food in a refrigerator leads to a decrease in temperature and an increase in disorder, resulting in an overall increase in entropy.