Assertion (A): Elementary reactions have same value of order and molecularity.
Reason (R): Molecularity is the number of molecules that participate in the reaction, while order is an experimental quantity.

Options

A. Both A and R are true and R is the correct explanation for A
B. Both A and R are true but R is NOT the correct explanation of A
C. A is true but R is false
D. A is false and R is true

Explanation

To solve the question, we need to analyze the assertion and the reason provided.

### Step 1: Understanding the Assertion
The assertion states that "Elementary reactions have the same value of order and molecularity."
- **Elementary reactions** are reactions that occur in a single step and involve a direct interaction between the reactants.
- The **order** of a reaction is defined as the sum of the powers of the concentration terms in the rate law expression. For an elementary reaction, the order is equal to the stoichiometric coefficients of the reactants.
- The **molecularity** of a reaction refers to the number of reactant molecules that collide to produce the reaction. For elementary reactions, molecularity can be determined directly from the balanced equation.

### Step 2: Analyzing the Reason
The reason states that "Molecularity is the number of molecules that participate in the reaction, while order is an experimental quantity."
- This statement is accurate. Molecularity is a theoretical concept that describes the number of molecules involved in the reaction, while the order of reaction is determined experimentally through rate measurements.

### Step 3: Conclusion
Both the assertion and the reason are true. However, the reason does not adequately explain the assertion because it does not directly address why the order and molecularity are the same for elementary reactions. Therefore, the answer to the question is that both the assertion and the reason are true, but the reason is not the correct explanation of the assertion.

### Final Answer
The assertion (A) is true, and the reason (R) is true, but R is not the correct explanation of A. Thus, the correct option is option 2.

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