The rate constant of a first order reaction is $3\times {10}^{-6}$ per second. If the initial concentration is 0.10 M, the initial rate of reaction is

Given: Rate constant of the first order reaction 

$\left(\mathrm{K}\right)=3\times {10}^{-6}$ per sec and initial concentration 

$\left[\mathrm{A}\right]=0.10\mathrm{M}$. We know that initial rate 

$\mathrm{r}=\mathrm{K}\left[\mathrm{A}\right]=3\times {10}^{-6}\times 0.10=3\times {10}^{-7}{\text{ Ms}}^{-1}.$