When $KMnO_4$ reacts with $Br^-$ in a basic medium to give bromate ion,the oxidation state of $Mn$ changes from $7$ to . . . . . .

Find the equivalent weight of $MnO_4^{-}$ for acid medium reactions. (Atomic weight of $Mn = 55$,Atomic weight of $O = 16$)

Write the net ionic equation for the reaction of potassium dichromate$(VI)$,$K_{2}Cr_{2}O_{7}$ with sodium sulphite,$Na_{2}SO_{3}$ in an acidic solution to give chromium$(III)$ ion and the sulphate ion.

In balancing the half-reaction $S_2O_3^{2-} \to S_{(s)}$,the number of electrons that must be added is:

$KMnO_4$ acts as an oxidising agent in alkaline medium. When alkaline $KMnO_4$ is treated with $KI$,iodide ion is oxidized to

$KMnO_4$ reacts with $H_2O_2$ in an acidic medium. The number of moles of oxygen produced per mole of $KMnO_4$ is