A : A positive catalyst increases the rate of reaction .
R : A positive catalyst alters reaction mechanism and decreases activation energy.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion , then mark (1).
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion , then mark (2).
C. If Assertion is true statement but Reason is false, then mark (3).
D. If both Assertion and Reason are false statements , then mark (4)

Answer

To solve the question regarding the assertion and reason about positive catalysts, we will analyze each statement step by step.

### Step 1: Analyze the Assertion
The assertion states: "A positive catalyst increases the rate of reaction."
- **Explanation**: Catalysts are substances that increase the rate of a chemical reaction without being consumed in the process. A positive catalyst specifically enhances the reaction rate.
- **Conclusion**: The assertion is **True**.

### Step 2: Analyze the Reason
The reason states: "A positive catalyst alters reaction mechanism and decreases activation energy."
- **Explanation**: A positive catalyst works by providing an alternative pathway for the reaction that has a lower activation energy compared to the uncatalyzed reaction. This change in the reaction mechanism allows the reactants to convert to products more easily.
- **Conclusion**: The reason is also **True**.

### Step 3: Determine if the Reason Explains the Assertion
- The reason explains how a positive catalyst increases the rate of reaction by decreasing the activation energy, which is a fundamental principle in chemical kinetics.
- **Conclusion**: The reason is a correct explanation for the assertion.

### Final Conclusion
Both the assertion and reason are true, and the reason correctly explains the assertion. Therefore, the correct answer is:
- **Option 1**: Both assertion and reason are true, and the reason is the correct explanation of the assertion.

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