Assertion (A) : The rate constant of a zero order reaction has same units as the rate of reaction.
Reason (R ): Rate constant of a zero order reaction does not depend upon the units of concentration.

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.

Explanation

To solve the given question, we need to analyze both the assertion (A) and the reason (R) provided.

### Step-by-Step Solution:

1. **Understanding Zero Order Reactions**:
- In a zero-order reaction, the rate of reaction is independent of the concentration of the reactants. This means that the rate remains constant regardless of how much reactant is present.

2. **Rate Equation for Zero Order Reactions**:
- The rate of a zero-order reaction can be expressed as:
\[ \text{Rate} = k[A]^0 = k \]
- Here, \( k \) is the rate constant and \([A]\) is the concentration of the reactant. Since any number raised to the power of zero is 1, the equation simplifies to the rate being equal to \( k \).

3. **Units of the Rate Constant (k)**:
- The units of the rate constant \( k \) for a zero-order reaction can be derived from the general formula for the rate constant:
\[ \text{Units of } k = \text{(mole/L)}^{1-n} \cdot \text{s}^{-1} \]
- For a zero-order reaction, \( n = 0 \):
\[ \text{Units of } k = \text{(mole/L)}^{1-0} \cdot \text{s}^{-1} = \text{mole/L} \cdot \text{s}^{-1} \]

4. **Units of Rate of Reaction**:
- The rate of reaction is also expressed in terms of concentration change over time, which has the same units as \( k \):
\[ \text{Rate} = \frac{\Delta [A]}{\Delta t} \quad \text{(change in concentration over time)} \]
- Thus, the units of rate of reaction are also \(\text{mole/L} \cdot \text{s}^{-1}\).

5. **Conclusion on Assertion (A)**:
- Since both the rate constant \( k \) and the rate of reaction have the same units of \(\text{mole/L} \cdot \text{s}^{-1}\), the assertion (A) is correct.

6. **Analyzing Reason (R)**:
- The reason states that the rate constant of a zero-order reaction does not depend upon the units of concentration. This is true because the rate of a zero-order reaction is constant and does not change with varying concentrations of reactants.
- Therefore, the reason (R) is also correct.

7. **Final Evaluation**:
- Both assertion (A) and reason (R) are correct, and R provides the correct explanation for A. Hence, the correct answer is that both A and R are correct, and R is the correct explanation of A.

### Final Answer:
Both A and R are correct, and R is the correct explanation of A.

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