Assertion (A) : If the activation energy of a reaction is zero, temperature will have no effect on the rate constant. Reason (R ): Lower the activation energy, faster is the reaction.

Options

A. If both `(A)` and `(R )` are correct, and `(R )` is the correct explnation of `(A)`.
B. If both `(A)` and `(R )` are correct, but `(R )` is noth the correct explanation of `(A)`.
C. If `(A)` is correct, but `(R )` is incorrect.
D. If `(A)` is incorrect, but `(R )` is correct.

Answer

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

**Assertion (A):** If the activation energy of a reaction is zero, temperature will have no effect on the rate constant.

**Reason (R):** Lower the activation energy, faster is the reaction.

### Step-by-Step Solution:

1. **Understanding Activation Energy (Ea):**
- Activation energy is the minimum energy required for a reaction to occur. It is a crucial factor in determining the rate of a reaction.

2. **Rate Constant Equation:**
- The rate constant \( k \) is given by the Arrhenius equation:
\[ k = A e^{-\frac{E_a}{RT}} \]
where:
- \( A \) = pre-exponential factor (frequency factor)
- \( E_a \) = activation energy
- \( R \) = universal gas constant
- \( T \) = temperature in Kelvin

3. **Analyzing the Assertion (A):**
- If \( E_a = 0 \), the equation simplifies to:
\[ k = A e^{0} = A \]
- This means that the rate constant \( k \) becomes equal to the pre-exponential factor \( A \) and is independent of temperature \( T \). Therefore, the assertion is correct.

4. **Analyzing the Reason (R):**
- The reason states that lower activation energy leads to a faster reaction. This is also true because a lower \( E_a \) results in a higher value of \( k \), which means a faster reaction rate.
- However, while this statement is true, it does not explain why the rate constant is independent of temperature when \( E_a = 0 \).

5. **Conclusion:**
- Both the assertion and the reason are correct statements. However, the reason provided does not correctly explain the assertion. Thus, the assertion is true, the reason is true, but the reason is not the correct explanation for the assertion.

### Final Answer:
- Both Assertion (A) and Reason (R) are correct, but Reason (R) is not the correct explanation for Assertion (A).

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