The second law of thermodynamics says that?

Question

I looked up the law and second law of thermodynamics and none of these seem to be the answer..

a. in every energy change some usefulness is lost

b. only energy can be wasted

c. we are running out of energy

d. efficiencies can be larger than 100 percent

e. all of these are true

I know c isn't the answer which means e isnt an answer but that is as far as i have narrowed it down too.

Answer 1

The Kelvin statement of the Second Law says: "It is impossible to convert heat completely into work" therefore this seems to suggest that answer a) would be correct.

Answer 2

it states that ...the entropy ( i.e. sponaniety) of the universe always increases in course of any spontaneous change......

here entropy can be assumed to be randomness

as two gases mix up with each other when releases in a room shows that the entropy increases.........

Answer 3

A

Answer 4

Choice A is the best answer. The second law of thermodynamics states that entropy (randomness) always increases. We can consider this from going to a more useful to less useful state; for instance, if I drop a coffee cup and it shatters on the floor, the entropy (randomness) increased, and as a result the coffee cup became less useful.

Answer 5

A is the best answer but is not very good. It's also not quite true, since the entropy change in a quasistatic process can be zero.

To be rigorous about it, here are two accurate statements of the second law:

The Clausius statement: No thermodynamic process is possible in which the only event is the transfer of heat energy from a cooler body to a warmer one.

The Kelvin-Planck statement: No thermodynamic process is possible in which the only event is the conversion of heat energy into work.

Answer 6

The answer A makes the most sense, since 2nd Law is all about entropy, which states entropy will decrease for spontaneous processes (theoretically you can be isentropic - but in reality eeeeh).