Question
The half-life of a first-order reaction is 20 minutes. What is the rate constant (in min^ -1 ) for this reaction?
MHT CET
Chemistry
Chemical Kinetics
2026
MHT CET 2026 (13 April Shift 2)
MHT CET Chemistry Question (2026) — Solution
Options
- A. 0.0347
- B. 0.5
- C. 13.86
- D. 34.67
Answer
A. 0.0347
Step-by-step solution
For a first-order reaction, the rate constant k is related to the half-life t_ 1/2 by the equation: k = 0.693 t_ 1/2 Given t_ 1/2 = 20 minutes. Substituting the value: k = 0.693 20 k = 0.03465 min ^ -1 Rounding off, we get k 0.0347 min ^ -1 . Answer: 0.0347
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