Q22 / 160 · TS EAMCET 2023 (12 May Shift 1) · Chemistry

If benzene diazonium chloride undergoes first order decomposition at $\mathrm{T}(\mathrm{K})$ with a rate constant of $6.93 \times 10^{-2}$ $\mathrm{min}^{-1}$, the time for completion of $90 \%$ of the reaction (in $\min )$ is (nearest integer) $(\log 2=0.30, \log 3=0.477)$

  • A
    $15$
  • B
    $30$
  • Correct answer
    C
    $33$
  • D
    $43$

Solution

for a first order reaction; $t=\frac{2.303}{K} \log \frac{a}{a-x}$ Now, for $90 \%$ completion, $a=100$ and $a-x$ $\begin{aligned} & =100-90=10 . \\ & \Rightarrow \mathrm{t}=\frac{2.303}{6.93 \times 10^{-2}} \log \frac{100}{10} \\ & =33.23 \mathrm{~min} . \end{aligned}$

Hence, the correct answer is option: 'C'.

Relevant Questions