Question

KMnO₄ acts as an oxidising agent in acidic medium. The number of moles of KMnO₄ that will be needed to react with one mole of sulphide ions in acidic solution is
(a) $\frac{2}{5}$
(b) $\frac{3}{5}$
(c) $\frac{4}{5}$
(d) $\frac{1}{5}$

Answer 1

The reaction will be

2KMnO4 + 5 H2SO3 --> K2SO4 +2 MnSO4 +2 H2SO4 + 3H2O

As 5 mole of sulphite reacts with 2 mole of  KMnO4 

Then 1 mole will react with 2/5 mole of KMnO4