If the concentration of the reactants is increased, the rate of reaction for first order-

Options

A. Remains unaffected
B. Increases
C. Decreases
D. May increase or decrease

Answer

To solve the question regarding the effect of increasing the concentration of reactants on the rate of a first-order reaction, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Definition of a First-Order Reaction**:
- A first-order reaction is one where the rate of reaction is directly proportional to the concentration of one reactant. The general form of the rate law for a first-order reaction can be expressed as:
\[ \text{Rate} = k[A] \]
where \( k \) is the rate constant and \( [A] \) is the concentration of the reactant.

2. **Identify the Relationship Between Concentration and Rate**:
- In the equation \( \text{Rate} = k[A] \), it is clear that the rate of the reaction depends linearly on the concentration of reactant \( A \). This means that if the concentration of \( A \) increases, the rate of reaction will also increase.

3. **Analyze the Effect of Increasing Concentration**:
- If we increase the concentration of \( A \) (let's say from \( [A_1] \) to \( [A_2] \), where \( [A_2] > [A_1] \)), we can express the new rate as:
\[ \text{New Rate} = k[A_2] \]
- Since \( [A_2] > [A_1] \), it follows that:
\[ \text{New Rate} > k[A_1] \]
- Therefore, the new rate is greater than the original rate, indicating that the rate of reaction increases with the increase in concentration.

4. **Conclusion**:
- From the above analysis, we conclude that for a first-order reaction, increasing the concentration of the reactant leads to an increase in the rate of reaction. Thus, the answer to the question is that the rate of reaction will increase.

### Final Answer:
If the concentration of the reactants is increased, the rate of reaction for a first-order reaction will also increase.

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