Question

Assertion (A) : Order of reaction is not applicable for elementary reaction but applicable for complex reaction. Reason (R) : Order of reaction is an experimental quantity.

• A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
• B. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
• C. Assertion (A) is true, but Reason (R) is false.
• D. Assertion (A) is false, but Reason (R) is true.

Hint:

Molecularity is defined only for elementary reactions, whereas order of reaction is obtained experimentally and can be assigned to both elementary and complex reactions.

Answer 1

The Correct Option is D

Step 1: Order IS applicable to elementary reactions.
For an elementary step $A + B \rightarrow \text{Products}$, the rate law follows directly from stoichiometry: Rate $= k[A][B]$, giving order $= 2$. Order is perfectly applicable to elementary reactions. Assertion is FALSE.
Step 2: Verify the Reason.
Order of reaction is determined experimentally as the sum of the exponents of concentration terms in the rate law. It cannot in general be deduced from the balanced equation alone. Reason is TRUE.
Step 3: Conclusion.
Assertion is false because order applies to both elementary and complex reactions. The Reason is independently correct as an experimental fact, but does not explain a false Assertion. \[ \boxed{\text{Option (D): Assertion false, Reason true}} \]