A : The molecularity of reaction can never be fractional.
R : Molecularity is the number of molecules needed to form activated complex, which will never be fractional.

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 assertion and reason question, we will analyze both statements step by step.

### Step 1: Understanding Molecularity
Molecularity refers to the number of reactant molecules that collide simultaneously to bring about a chemical reaction. It can be classified as:
- **Unimolecular**: 1 molecule (e.g., A → B)
- **Bimolecular**: 2 molecules (e.g., A + B → C)
- **Trimolecular**: 3 molecules (e.g., A + B + C → D)

**Hint**: Recall that molecularity is based on the number of molecules involved in the rate-determining step of a reaction.

### Step 2: Analyzing the Assertion
The assertion states that "The molecularity of a reaction can never be fractional." This is true because molecularity is defined as a whole number, representing the count of molecules involved in the reaction.

**Hint**: Think about how you can count molecules; you can't have half a molecule participating in a reaction.

### Step 3: Analyzing the Reason
The reason states that "Molecularity is the number of molecules needed to form an activated complex, which will never be fractional." This statement is also true. The activated complex (or transition state) forms when reactant molecules collide effectively. If molecularity were fractional, it would imply that a part of a molecule is participating, which is not possible.

**Hint**: Consider what it means for molecules to collide effectively; they must be whole entities.

### Step 4: Relationship Between Assertion and Reason
Both the assertion and reason are true, but the reason does not provide a correct explanation for the assertion. The assertion stands on its own based on the definition of molecularity, while the reason explains why molecularity is whole but does not explain why it cannot be fractional.

**Hint**: Evaluate whether the reason logically supports the assertion or if it merely states a fact.

### Conclusion
In conclusion, both the assertion and reason are true, but the reason is not the correct explanation for the assertion. Therefore, the answer is that both statements are true, but the reason is not the correct explanation of the assertion.

**Final Answer**: Both assertion and reason are true, but the reason is not the correct explanation of the assertion.