For $$n$$th order of reaction, half-life period is directly proportional to

Half-life of a reaction is found to be inversely proportional to the fifth power of its initial concentration, the order of reaction is

A first order reaction is half completed in $$45 \mathrm{~min}$$. How long does it need $$99.9 \%$$ of the reaction to be completed?

The rate of the reaction, $$\mathrm{CH}_3 \mathrm{COOC}_2 \mathrm{H}_5+\mathrm{NaOH} \longrightarrow \mathrm{CH}_3 \mathrm{COONa}+\mathrm{C}_2 \mathrm{H}_5 \mathrm{OH}$$ is given by the equation, rate $$=k\left[\mathrm{CH}_3 \mathrm{COOC}_2 \mathrm{H}_5\right][\mathrm{NaOH}]$$. If concentration is expressed in $$\mathrm{mol} \mathrm{L}^{-1}$$, the unit of $$k$$ is