Question

The number of moles of $KMn{O}_4$ that will be needed to react with one mole of sulphite ion in acidic solution is :

• A. $\frac{2}{5}$
• B. $\frac{3}{5}$
• C. $\frac{4}{5}$
• D. $1$

Answer 1

The correct option is A $\frac{2}{5}$

The balanced chemical reaction is as given below,

$2Mn{O}_4^{-}+5S{O}_3^{2-}+6H^{+}\to 2M{n}^{2+}+5S{O}_4^{2-}+3H_{2}O$

$5$ moles of $S{O}_3^{2-}$ reacts with $2$ moles of $KMn{O}_4$.

Hence, $1$ mole of $S{O}_3^{2-}$ will react with $\frac{2}{5}$ moles of $KMn{O}_4$.