Question

The rate for a first order reaction is $0.6932\times {10}^{-2}$ mol litre${}^{-1}$ min${}^{-1}$ and the initial concentration of the reactant is 1 M, $t_{1/2}$ is equal to:

• A. 0.693 x ${10}^{-2}$ minute
• B. 100 minutes
• C. 0.693 x ${10}^{-3}$ minute
• D. 6.932 minutes

Answer 1

The correct option is B 100 minutes

Rate $=k\left[A\right]$

$k=\frac{0.6932\times {10}^{-2}}{1}$
$t_{{}^1{/}_2}=\frac{0.693}{k}$
$=\frac{0.693}{0.693\times {10}^{-2}}$

$=100min$

Hence, the correct option is $\text{B}$.