Assertion:In electrolysis of aqueous NaCl the product obtained is `H_2` gas.
Reason:Gases are liberted faster than the metals.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion .
B. If both assertion and reason are true but reason is not the correct explanation of assertion .
C. If assertion is true but reason is false .
D. If both assertion and reason are false .

Explanation

To solve the question, we need to analyze both the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that during the electrolysis of aqueous NaCl, hydrogen gas is produced.
- In the electrolysis process, we have two main reactions occurring at the electrodes. At the cathode, we can have:
- \( \text{Na}^+ + e^- \rightarrow \text{Na (s)} \) with a standard reduction potential of -2.71 V.
- \( \text{H}^+ + e^- \rightarrow \text{H}_2 (g) \) with a standard reduction potential of 0.00 V.

2. **Evaluating the Reactions**:
- The reaction producing hydrogen gas has a higher (less negative) standard reduction potential compared to the reaction producing sodium metal. This means that the reduction of hydrogen ions to hydrogen gas is more favorable than the reduction of sodium ions to sodium metal.

3. **Conclusion on the Assertion**:
- Since the reaction producing hydrogen gas is more favorable, it will occur at the cathode. Therefore, the assertion is **correct**: hydrogen gas is indeed produced during the electrolysis of aqueous NaCl.

4. **Understanding the Reason**:
- The reason states that gases are liberated faster than metals.
- In electrolysis, the rate of gas evolution can depend on various factors, including the overpotential and the nature of the ions involved. However, typically, metals are deposited at a faster rate than gases are evolved during electrolysis.

5. **Conclusion on the Reason**:
- The reason is **incorrect** because metals are generally liberated faster than gases during electrolysis.

6. **Final Evaluation**:
- The assertion is true, and the reason is false. Therefore, the correct answer is that the assertion is correct, and the reason is incorrect.

### Final Answer:
- Assertion: True
- Reason: False