Question

A first order reaction has a half life period of 69.3 sec. At 0.10 mol $L^{-1}$ reactant concentration, the rate will be:

• A. ${10}^{-4}M{sec}^{-1}$
• B. ${10}^{-3}M{sec}^{-1}$
• C. ${10}^{-1}M{sec}^{-1}$
• D. $6.93\times {10}^{-1}M{sec}^{-1}$

Answer 1

The correct option is B ${10}^{-3}M{sec}^{-1}$

First order rkt $t_{1/2}=69.3$

$\Rightarrow \frac{ln2}{k}=69.3$

$\Rightarrow k=\frac{ln2}{69.3}=\frac{0.693}{69.3}$

$={10}^{-2}$

$\therefore r=k\left[R\right]$

$={10}^{-2}\times {10}^{-1}$

$={10}^{-3}M/s$