Question

Rate constant of decomposition of hydrogen peroxide is \(0.0204 \text{minutes}^{-1}\), calculate half life of reaction.

• A. \(17.56\) minutes
• B. \(33.97\) minutes
• C. \(51.50\) minutes
• D. \(68.70\) minutes

Hint:

For a first-order reaction t half = 0.693 divided by k.

Answer 1

The Correct Option is B

Step 1: Idea:
Half-life is the time for the concentration to halve: $kt_{1/2} = \ln 2 = 0.693$.

Step 2: Work:
$t_{1/2} = 0.693 \div 0.0204 = 33.97$ min.

Step 3: Sanity Check:
After about 34 min, the rate has fallen to half, which is consistent with a small $k$ of 0.02 per minute. Answer (B).

Final Answer:
Option (B). \[ \boxed{\text{(B) } 33.97\ \text{min}} \]