Determine the volume of $\frac{\mathrm{M}}{8}{\mathrm{KMnO}}_4$ solution required to react completely with $20 {\mathrm{Cm}}^3$ of $\frac{\mathrm{M}}{4}{\mathrm{FeSO}}_4$ solution in acidic medium.

Which of the following species, do not show disproportionation reaction and why?

${\mathrm{ClO}}^{-}, {\mathrm{ClO}}_2^{-}, {\mathrm{ClO}}_3^{-}$ and ${\mathrm{ClO}}_4^{-}$

Also write reaction for each of the species that disproportionates.

Balance the following equation :

${\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}+{\mathrm{H}}^{+}+{\mathrm{S}}^{2-} \to {\mathrm{Cr}}^{3+}+\mathrm{S}+{\mathrm{H}}_2\mathrm{O}$