Oxidation of thiosulphate $S_2O_3^{2-}$ ion by iodine gives

The following reaction occurs in acidic medium: $KMnO_4 + 8 H^{+} + 5 e^{-} \longrightarrow K^{+} + Mn^{2+} + 4 H_2O$. What is the equivalent weight of $KMnO_4$? (Molecular weight of $KMnO_4 = 158$)

The number of moles of $K_2Cr_2O_7$ reduced by $1 \, mol$ of $Sn^{2+}$ is:

The product of oxidation of $I^{-}$ with $MnO_4^{-}$ in alkaline medium is

What is the product of the oxidation of $I^-$ by $MnO_4^-$ in an alkaline medium?

Chlorine is used to purify drinking water. Excess of chlorine is harmful. The excess of chlorine is removed by treating with sulphur dioxide. Present a balanced equation for this redox change taking place in water.