What does the second law of thermodynamics say about entropy?

A. Only changes in entropy can be measured.
B. The entropy in a system is zero at equilibrium.
C. The entropy in a system and its surroundings tends to increase.
D. Entropy cannot be created or destroyed.

I think c.

I agree with c.

it is C

That is correct! According to the second law of thermodynamics, the entropy in a system and its surroundings tends to increase. Therefore, option C is the correct answer.

The correct answer is indeed option C: The entropy in a system and its surroundings tends to increase.

To understand why this is the case, let's first explain what entropy is. Entropy is a measure of the disorder or randomness in a system. The second law of thermodynamics states that the entropy of an isolated system tends to increase over time.

To get to the answer, we can eliminate options A and B. Option A is incorrect because changes in entropy can indeed be measured. Option B is incorrect because the entropy of a system is not necessarily zero at equilibrium, but rather the rate of change of entropy becomes zero.

Now, let's focus on options C and D. Option D is a statement of the first law of thermodynamics, which says that energy cannot be created or destroyed, only transferred or converted from one form to another. While this is true, it is not specifically related to entropy.

To distinguish between options C and D, we need to consider the concept of entropy. In any spontaneous process, which is a process that occurs naturally without intervention, the total entropy of the system and its surroundings tends to increase. This means that in a closed system, where no energy or matter is exchanged with the surroundings, the entropy will always increase over time.

Therefore, the correct answer is option C: The entropy in a system and its surroundings tends to increase.