Chemical Kinetics: Mixed MCQ

Solve this quality-checked JEE multiple-choice question, then review the correct answer and explanation.

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MixedHardQuestion 720018

Question

For a reaction with activation energy 100 kJ mol⁻¹, if a catalyst reduces Ea to 70 kJ mol⁻¹ at 300 K, the ratio of catalysed to uncatalysed rate constant (k_cat/k_uncat) is approximately (R = 8.314 J mol⁻¹ K⁻¹):

A
e^12
Correct
B
e^(−12)
C
e^6
D
e^(−6)

Correct answer

e^12

Explanation

ln(k_cat/k_uncat) = (Ea_uncat − Ea_cat)/(RT) = (100000 − 70000)/(8.314 × 300) = 30000/2494 ≈ 12. So k_cat/k_uncat = e^12 ≈ 1.6×10⁵.

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