Question

It is given that the thermodynamic system changes from state A to state B and then back to state A. It is given that the process is reversible. Choose the correct statements.
(A) The states occurring between A to B are the same as states occurring between B to A
(B) The states occurring between A to B may be different from the states occurring between B to A
(C) The energy required for transition from state A to state B is same as the energy required for the transition from state B to state A
(D) The states occurring between A to B cannot be measured

Answer 1

Hint
First we have to know about the first law of thermodynamics, second law of thermodynamics and third law of thermodynamics. Second law of thermodynamics gives an explanation about the reversible process. By using the second law of thermodynamics, the solution can be determined.

Complete step by step solution
First law of thermodynamics: Energy cannot be created nor destroyed. It can be changed from one form of energy to another form of energy. The total amount of energy in the universe remains constant, it changes from one form to another.
Second law of thermodynamics: Second law of thermodynamics states that the total entropy of an isolated system can never be decreased, and the entropy is constant if all the processes are reversible.
Third law of thermodynamics: Third law of thermodynamics states that the entropy of a system at absolute zero is a well-defined constant.
In thermodynamics, the reversible process is a process in which the direction of the process is reversed, with no entropy changes. As said earlier in the second law of thermodynamics. So, if the thermodynamic system changes from state A to state B and returns back from state B to state A, then the process is reversible. In the reversible process, the states occurring between A to B are the same as states occurring between B to A.
Thus option (A) is correct.

Note
The states occurring between A to B are the same as states occurring between B to A, because the entropy of the universe can never be changed during the reversible process. And the three laws of thermodynamics are the most important statements for any thermodynamic system.