The rate of reaction is always equal to the rate constant. The order of the reaction. Will be

Options

A. First order
B. Second order
C. Half order
D. Zero order

Answer

To determine the order of the reaction when the rate of reaction is always equal to the rate constant, we can analyze the relationship between the rate of reaction, the rate constant, and the concentration of reactants.

### Step-by-Step Solution:

1. **Understanding the Rate Law**:
The rate of a reaction can be expressed using the rate law:
\[ \text{Rate} = k [A]^n \]
where \( k \) is the rate constant, \( [A] \) is the concentration of reactant A, and \( n \) is the order of the reaction.

2. **Setting the Condition**:
According to the problem, we need to find when the rate of reaction is equal to the rate constant:
\[ \text{Rate} = k \]

3. **Substituting the Rate Law**:
We can substitute the rate law into the condition:
\[ k [A]^n = k \]

4. **Dividing Both Sides by \( k \)**:
Assuming \( k \neq 0 \), we can divide both sides of the equation by \( k \):
\[ [A]^n = 1 \]

5. **Analyzing the Concentration**:
The equation \( [A]^n = 1 \) implies that the concentration of A raised to the power of \( n \) must equal 1. This can happen under specific conditions:
- If \( n = 0 \), then \( [A]^0 = 1 \) regardless of the concentration of A.
- If \( n > 0 \), then \( [A] \) must equal 1 for the equation to hold true, which is not generally applicable as concentrations can vary.

6. **Conclusion**:
Therefore, the only order of reaction that satisfies the condition that the rate of reaction is always equal to the rate constant is when \( n = 0 \). This indicates a zero-order reaction.

### Final Answer:
The order of the reaction is **0** (zero order).

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