A : In presence of +ve catalyst, activation energy & threshold energy decreases.
R : Minimum energy required to permit a reaction is known as threshold 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, we need to analyze both the assertion and the reason provided.

### Step 1: Understand the Assertion
The assertion states: "In presence of a positive catalyst, activation energy and threshold energy decreases."

- A positive catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process.
- It works by providing an alternative reaction pathway with a lower activation energy.
- Activation energy (Ea) is the minimum energy required for a reaction to occur, while threshold energy is the minimum energy required to permit a reaction to take place.

### Step 2: Analyze the Effect of a Catalyst
When a catalyst is present:
- The energy barrier that reactants must overcome to form products is lowered.
- This means that both the activation energy and the threshold energy decrease.

### Step 3: Understand the Reason
The reason states: "Minimum energy required to permit a reaction is known as threshold energy."

- This statement is true. The threshold energy is indeed the minimum energy needed for the reactants to undergo a reaction.

### Step 4: Determine the Truth of Both Statements
- Both the assertion and the reason are true.
- However, the reason does not provide a direct explanation for the assertion. The assertion discusses the effect of a catalyst on activation energy and threshold energy, while the reason simply defines threshold energy.

### Step 5: Conclusion
Since both statements are true but the reason does not explain the assertion, the correct answer is that both assertion and reason are true, but the reason is not the correct explanation of the assertion.

### Final Answer
The correct option is **Option 2**: Both assertion and reason are true, but the reason is not the correct explanation of the assertion.

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