When potassium permanganate is titrated against ferrous ammonium sulphate, the equivalent weight of potassium permanganate is

$$\begin{gathered} \mathrm{In} \mathrm{Mohr}\text{'}\mathrm{s} \mathrm{salt}, \\ [{\mathrm{Fe}}^{+2}\to {\mathrm{Fe}}^{+3}+{\mathrm{e}}^{-}]\times 5 \\ {\mathrm{MnO}}_4^{-2}+8{\mathrm{H}}^{+}+5{\mathrm{e}}^{-}\to {\mathrm{Mn}}^{+2}+4{\mathrm{H}}_2\mathrm{O} \\ \mathrm{Overall} \mathrm{reaction} \mathrm{is} \\ {\mathrm{MnO}}_4^{-2}+8{\mathrm{H}}^{+}+5{\mathrm{Fe}}^{+2}\to {\mathrm{Mn}}^{+2}+5{\mathrm{Fe}}^{+3}+4{\mathrm{H}}_2\mathrm{O} \end{gathered}$$

Total change in Oxidation state = 5
$\mathrm{E}=\frac{\mathrm{M}}{5}$