Question

1. If a system undergoes a reversible process,

a	it must be possible to restore the system to its original state.
b	it must be possible to restore the surroundings to their original state.
c	it must be possible to restore both the system and the surroundings to their original states.
d	it is impossible to restore either the the system or the surroundings to their original states.
e	the system must not interact with its surroundings. 2. According to the second law of thermodynamics, for any process that may occur within an isolated system, which one of the choices applies? a Entropy remains constant. b Entropy increases. c Entropy decreases. d Both A and B are possible. e Both A and C are possible.

Answer 1

1. If a system undergoes a reversible process.

(c)	it must be possible to restore both the system and the surroundings to their original states.

A thermodynamic process is reversible if the process can return back in such a that both the system and the surroundings return to their original states, with no other change anywhere else in the universe. It means both system and surroundings are returned to their initial states at the end of the reverse process.

2. According to the second law of thermodynamics, for any process that may occur within an isolated system, which one of the choices applies?

(d)	Both A and B are possible.

The second law of thermodynamics states that the total entropy of an isolated system can never decrease over time. The total entropy of a system and its surroundings can remain constant in ideal cases where the system is in thermodynamic equilibrium, or is undergoing a (fictive) reversible process. In all processes that occur, including spontaneous processes, the total entropy of the system and its surroundings increases and the process is irreversible in the thermodynamic sense. The increase in entropy accounts for the irreversibility of natural processes, and the asymmetry between future and past.