Assertion (A): For a first order reaction, half-life period is independent of initial concentration of the reacting species.
Reason (R): The half-life of a reaction is the time in which the reactant concentration is reduced to one half of its initial concentration.

Options

A. Both A and R are true and R is the correct explanation for A
B. Both A and R are true but R is NOT the correct explanation of A
C. A is true but R is false
D. A is false and R is true

Explanation

To solve the question regarding the assertion and reason about first-order reactions, we can break it down into a step-by-step explanation.

### Step-by-Step Solution:

1. **Understanding the Assertion (A)**:
- The assertion states that for a first-order reaction, the half-life period is independent of the initial concentration of the reacting species.
- This is a well-known characteristic of first-order reactions. The half-life (T_half) for a first-order reaction is given by the formula:
\[ T_{half} = \frac{0.693}{k} \]
- Here, \(k\) is the rate constant. Notice that the initial concentration does not appear in this formula, confirming that the half-life is indeed independent of the initial concentration.

2. **Understanding the Reason (R)**:
- The reason states that the half-life of a reaction is the time in which the reactant concentration is reduced to one-half of its initial concentration.
- This definition is accurate and applies to all types of reactions, including first-order reactions.

3. **Analyzing the Relationship between Assertion and Reason**:
- Both the assertion and the reason are true statements.
- However, the reason does not directly explain why the half-life is independent of the initial concentration. It merely defines what half-life means.

4. **Conclusion**:
- Since both the assertion and the reason are true, but the reason does not correctly explain the assertion, we conclude that the assertion is true, the reason is true, but the reason is not the correct explanation for the assertion.

### Final Answer:
The assertion (A) is true, the reason (R) is true, but R is not the correct explanation of A.