JEE MainChemistryChemical Kinetics and Nuclear ChemistryNumerical+4 / −1
For a first order reaction A B, the rate constant, k = 5.5 10 14 s 1. The time required for 67% completion of reaction is x 10 1 times the half life of reaction. The value of x is (Nearest integer) (Given : log 3 = 0.4771)
Numerical answer
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Correct answer: 16
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For a first-order reaction,
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For completion, the reactant left is : Hence,
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The half-life for a first-order reaction is:
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Therefore,
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Now evaluate : This is awkward directly, so write: More neatly,
But the standard shortcut is: so
Also,
Hence,
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Given that so
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Nearest integer:
The derived answer matches the stored correct answer.
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