Question

Assertion (A): In a first order reaction, if the concentration of the reactant is doubled, its half-life is also doubled. Reason (R): The half-life of a reaction does not depend upon the initial concentration of the reactant in a first order reaction.

• 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:

For first-order reactions, the half-life remains constant regardless of the concentration of reactants, which is a key feature of such reactions.

Answer 1

The Correct Option is D

Step 1: For a first-order reaction, the half-life is independent of the initial concentration of the reactant, and it remains constant regardless of how the concentration changes. Thus, Assertion (A) is false, but Reason (R) is true. 

 Step 2: Thus, Assertion (A) is false, and Reason (R) is true.