JEE Main · 2022 · Shift-IImediumCK-017

For a first order reaction, the time required for completion of 90% reaction is 'x' times the half life of the…

Chemical Kinetics · Class 12 · JEE Main Previous Year Question

Question

For a first order reaction, the time required for completion of 90% reaction is ' $x$ ' times the half life of the reaction. The value of ' $x$ ' is (Given: $\ln 10 = 2.303$ and $\log 2 = 0.3010$ )

Options

a
1.12
b
2.43
c
3.32
✓
d
33.31

Correct Answerc

3.32

Detailed Solution

For first order: $t_{90\%} = \frac{2.303}{k}\log\frac{100}{10} = \frac{2.303}{k}$

$t_{1/2} = \frac{\ln 2}{k} = \frac{0.693}{k}$

$x = \frac{t_{90\%}}{t_{1/2}} = \frac{2.303/k}{0.693/k} = \frac{2.303}{0.693} = 3.32$

Answer: Option (3) — 3.32

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