Which of the following statement (s) is correct?
Statement-I: The entropy of isolated system with P-V work only, is always maximized at equillibrium.
Statement-2: It is possible for the entropy of closed system to decrease substantialy in an irreversible process.
Statemet-3: Entropy can be crearted but not destroyed.
Statement-4 `DeltaS_(system)` is zero for reversible process in an isolated system.

Options

A. Statement i, ii, iii
B. Statement ii, iv
C. Statement I, ii, iii
D. all of these

Answer

To solve the question regarding the correctness of the statements related to entropy, we will analyze each statement step by step.

### Step-by-Step Solution:

1. **Statement-I: The entropy of an isolated system with P-V work only is always maximized at equilibrium.**
- According to the second law of thermodynamics, the total entropy of an isolated system tends to increase until it reaches equilibrium. At equilibrium, the entropy is maximized. Therefore, this statement is **correct**.

2. **Statement-2: It is possible for the entropy of a closed system to decrease substantially in an irreversible process.**
- In an irreversible process, while the entropy of the system can decrease, the total entropy (system + surroundings) must increase. This is consistent with the second law of thermodynamics. Thus, this statement is also **correct**.

3. **Statement-3: Entropy can be created but not destroyed.**
- This statement aligns with the principles of thermodynamics. Entropy can increase (be created) in a system, but it cannot be destroyed. The total entropy of the universe tends to increase. Therefore, this statement is **correct**.

4. **Statement-4: ΔS_system is zero for a reversible process in an isolated system.**
- For a reversible process in an isolated system, the change in entropy (ΔS) of the system is indeed zero because the system is in equilibrium. Thus, this statement is also **correct**.

### Conclusion:
All statements (I, II, III, and IV) are correct. Therefore, the answer is that all statements are correct.