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

### Step 1: Understanding Molecularity
Molecularity is defined as the number of reacting species (atoms, molecules, or ions) that collide simultaneously to bring about a chemical reaction. It is an important concept in chemical kinetics.

**Hint:** Recall that molecularity refers to the number of particles involved in the reaction mechanism.

### Step 2: Analyzing the Assertion
The assertion states that "The molecularity of reaction can never be fractional." This is true because molecularity is based on whole molecules or particles that participate in the reaction. Since you cannot have a fraction of a molecule participating in a collision, molecularity must always be a whole number (1, 2, 3, etc.).

**Hint:** Think about how molecules interact in a reaction; they must be whole entities.

### 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 is also true. The activated complex (or transition state) is formed during the collision of reactant molecules. Since the number of molecules that collide to form this complex must be whole, the molecularity itself cannot be fractional.

**Hint:** Consider the concept of the activated complex and how it relates to the number of molecules involved.

### Step 4: Conclusion
Both the assertion and the reason are correct. Furthermore, the reason provided gives a valid explanation for the assertion. Therefore, the correct conclusion is that both statements are true, and the reason correctly explains the assertion.

**Hint:** When evaluating assertions and reasons, check if the reason logically supports the assertion.

### Final Answer
Both the assertion and the reason are correct, and the reason is the correct explanation of the assertion.