The number of moles $\mathrm{KMnO}_4$ that will be needed to react with one mole of sulphite ion in acidic…
The number of moles $\mathrm{KMnO}_4$ that will be needed to react with one mole of sulphite ion in acidic solution is:
$4 / 5$
$2 / 5$
1
$3 / 5$
Solution
The balanced chemical equation is:
$2 \mathrm{MnO}_4^{-}+ 6 \mathrm{H}^{+}+5 \mathrm{SO}_3^{--} \longrightarrow 2 \mathrm{Mn}^{++}+5 \mathrm{SO}_4^{--}+3 \mathrm{H}_2 \mathrm{O}$
From the equation it is clear that
Moles of $\mathrm{MnO}_4^{-}$ require to oxidise 5 moles of $\mathrm{SO}_3^{--}$are 2
Moles of $\mathrm{MnO}_4^{-}$ require to oxidise 1 mole of $\mathrm{SO}_3^{--}$are $2 / 5$.