Question

The incorrect statement(s) about this process is/are:

(I) Internal energy of the system decreases at the end of the cycle

(II) Entropy of the system increases at the end of the cycle

(III) System performs work on the surroundings during the cycle

(IV) Heat exchanged between system and surroundings is zero during the cycle

Choose the correct answer from the options given below:

• A. (I) and (II)
• B. (I), (II) and (III)
• C. (II) and (IV)
• D. (I), (II) and (IV)

Answer 1

Answer: (D)

(I), (II) and (IV)

Answer 2

For any complete thermodynamic cycle the state functions return to their original values. Thus:

1. Internal Energy (U): ΔU = 0 for a cycle. So statement (I) claiming U decreases is false.

2. Entropy (S) of the system: Since entropy is a state function, ΔS = 0 (for a reversible cycle). Hence, statement (II) is false.

3. Work (W): A clockwise cycle on a P–V diagram indicates that the system does net work on the surroundings. So statement (III) is true.

4. Heat (Q): From the first law, ΔU = Q - W = 0 implies Q = W. Since work is done by the system, heat is absorbed; therefore, statement (IV) is false.

The incorrect statements are (I), (II), and (IV).