STANDARDChemistry-Chemical Kinetics

STANDARD Chemistry First Order Reactions MCQ Question

Type: MCQ-numerical-Medium-Class 12

A first order reaction takes 40 min for 30% decomposition. What will be t₁/₂?

A

77.7 min.

B

52.5 min.

C

46.2 min.

D

22.7 min.

Correct Answer

Option A

Detailed Explanation

For a first order reaction, t₁/₂ = 0.693/k. The rate constant k is calculated using k = 2.303/t log(1/(1-x)), where x = 0.3 and t = 40 min. Substituting the values, k = 8.918 x 10⁻³ min⁻¹, giving t₁/₂ = 77.7 min.

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