Number of moles of $KMnO_{4}$ reduced by $1 \ mol$ of $I^{-}$ in basic medium is

The number of moles of sodium sulphite $(Na_2SO_3)$ needed to react with one mole of $KMnO_4$ in acidic solution is:

See the following chemical reaction:
$Cr_2O_7^{2-} + XH^{+} + 6Fe^{2+} \rightarrow YCr^{3+} + 6Fe^{3+} + ZH_2O$
The sum of $X$,$Y$ and $Z$ is $.......$.

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.

What is the equivalent weight of $SnCl_{2}$ in the following reaction: $SnCl_{2} + Cl_{2} \longrightarrow SnCl_{4}$?

In an acidic medium,the dichromate ion oxidizes the ferrous ion to the ferric ion. If the molar mass of potassium dichromate is $294 \, g/mol$,what is its equivalent mass?