Which statement is NOT correct?

Question

You are attempting to heat the inside of a shed by placing rocks into a hot spring(a geothermally heated natural spring), then moving the rocks inside the shed and letting them warm the room. Once the rocks no longer feel warm, the process is repeated.
A. If the heat capacity of the rockswere increased, it will take longer to them heat up, but they would stay warm for longer in the room.
B. This is not a heat engine.
C. If the rock is the system, then the entropy of the system is increasing when the rock is in the spring and decreasing when the rock is in the shed.
D. If the system is “the shed and everything inside it,” then the entropy of the system increases whenever heat is being added, and never decreases.
E. Increasing the time spent in the spring may increase the amount of heat delivered to the room by one cycle.

Answer 1

A. Incorrect. This is true. The higher the heat capacity, the greater the amount of stored energy the rocks hold (for a particular initial and
final temperature), which means it will take longer for this heat to be transferred to the air inside the shed.
B. Incorrect. This is true. Heat is being transferred, indirectly, from the spring to the inside of the shed. No conversion of heat into work is
involved so it is not a heat engine.
C. Incorrect. This is true. When heat is being added to the system, its entropy is increasing.
D. Correct. By this definition the rock is inside the system when it is inside the shed, and when it is removed, this represents a moutS ?_out term in the entropy balance which causes the entropy of the system to decrease at that point.
E. Incorrect. This is true. The problem statement doesn’t say how long the rocks are kept in the spring. If the temperature of the rocks doesn’t reach thermal equilibrium with the spring, then more time in the spring will allow the rocks to gain more heat and get closer to equilibrium.