A closed system is cooled reversibly from 100°C to 50°C. If no work is done on the system________________?

Question

Accepted Answer

its internal energy (U) decreases and its entropy (S) increases. A is correct because for a closed system cooled without work, internal energy decreases and entropy increases due to heat transfer. B is incorrect because the internal energy changes when temperature changes. C is incorrect because both internal energy and entropy change during cooling. D is incorrect because the internal energy must decrease when the temperature drops.