What is the time required for completion of $90 \%$ of a first order reaction?

What is the time required for completion of $90 \%$ of a first order reaction?
  1. $\frac{2.303}{k}$
  2. $\frac{0.3010}{\mathrm{k}}$
  3. $\frac{0.693}{2 \mathrm{k}}$
  4. $\frac{2 \times 0.693}{k}$

Solution

$\begin{aligned} & \mathrm{t}=\frac{2.303}{\mathrm{k}} \log \frac{\mathrm{a}_0}{\mathrm{a}_{\mathrm{t}}} \\ & \mathrm{t}=\frac{2.303}{\mathrm{k}} \log \frac{100}{10} \\ & \mathrm{t}=\frac{2.303}{\mathrm{k}}\end{aligned}$

Asked in: MHT CET 2022 (07 Aug Shift 1)

Practice more Chemical Kinetics questions on Aicharya