The unit of rate constant for a zero order reaction is:

The half life of a substance in a certain enzyme-catalysed reaction is $138 \mathrm{s}.$ The time required for the concentration of the substance to fall from $\mathrm{1.28 }\mathrm{mg} {\mathrm{L}}^{\mathrm{-1}} \text{to} 0.04 \mathrm{mg} {\mathrm{L}}^{\mathrm{-1}}$ is _____.

The rate of the reaction $2{\mathrm{N}}_2{\mathrm{O}}_5\to 4{\mathrm{NO}}_2+{\mathrm{O}}_2$ can be written in three ways :

$\frac{-\mathrm{d}\left[{\mathrm{N}}_2{\mathrm{O}}_5\right]}{\mathrm{dt}}=\mathrm{k}\left[{\mathrm{N}}_2{\mathrm{O}}_5\right]$

$\frac{\mathrm{d}\left[{\mathrm{NO}}_2\right]}{\mathrm{dt}}={\mathrm{k}}^{\text{'}}\left[{\mathrm{N}}_2{\mathrm{O}}_5\right]$

$\frac{\mathrm{d}\left[{\mathrm{O}}_2\right]}{\mathrm{dt}}={\mathrm{k}}^{\text{'}\text{'}}\left[{\mathrm{N}}_2{\mathrm{O}}_5\right]$

The relationship between $\mathrm{k}$ and ${\mathrm{k}}^{\text{'}}$and between $\mathrm{k}$ and $\mathrm{k}"$ are: