Which statement is true for reversible processes?

Options

A. It takes place in a single step
B. Driving force is much greater than opposing force
C. Work obtained is maximum
D. There is no work done in such processes

Answer

To determine which statement is true for reversible processes, let's analyze the characteristics of reversible processes step by step.

### Step-by-Step Solution:

1. **Definition of Reversible Processes**:
- A reversible process is a thermodynamic process that can be reversed without leaving any trace on the surroundings. This means that both the system and the surroundings can be returned to their original states.

2. **Characteristics of Reversible Processes**:
- Reversible processes occur infinitely slowly, allowing the system to remain in thermodynamic equilibrium throughout the process.
- The work done in a reversible process is maximized compared to irreversible processes.

3. **Work Done in Reversible Processes**:
- The work done during a reversible process can be represented by the area under the P-V (pressure-volume) curve. Since the process is carried out slowly, the area under the curve is maximized.

4. **Comparison with Irreversible Processes**:
- In irreversible processes, the work done is less than that in reversible processes because they occur rapidly and do not maintain equilibrium. The work done is calculated as the sum of instantaneous points, which results in a smaller area under the P-V curve.

5. **Evaluating Statements**:
- **Statement A**: "It takes in a single step." - This is false; reversible processes occur in an infinite number of infinitesimally small steps.
- **Statement B**: "Driving force is much greater than opposing force." - This is also false; in a reversible process, the driving force is equal to the opposing force at equilibrium.
- **Statement C**: "Work done is maximum." - This is true; the work done in a reversible process is indeed the maximum possible work.
- **Statement D**: "There is no work done in such process." - This is false; work is done in reversible processes, as indicated by the area under the P-V curve.

### Conclusion:
The correct statement regarding reversible processes is **Statement C: Work done is maximum**.

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