The units of the rate constant of zero order reaction are

For nth order reaction, the units of rate constant are ${\mathrm{Mol}}^{1-\mathrm{n}}{\mathrm{L}}^{\mathrm{n}-1}{\mathrm{S}}^{-1}.$For zero order reaction, n = 0 . Therefore, the units of rate constant, k is ${\mathrm{mol}}^{1-0}{\mathrm{L}}^{0-1}{\mathrm{S}}^{-1}.\mathrm{i}.\mathrm{e} \mathrm{mole} {\mathrm{L}}^{-1}{\mathrm{S}}^{-1}$