The number of moles of `KMnO_(4)` that will be needed to react with one mole of sulphite ion in acidic solution is

Options

A. `4//5`
B. `2//5`
C. `1`
D. `3//5`

Answer

B

Explanation

Ionic equation for the reaction is
`2MnO_(4)^(-)+6H^(+)+5SO_(3)^(2-)to2Mn^(2-)+5SO_(4)^(2-)+3H_(2)O`
5 moles of `SO_(3)^(2-)` ions are oxidized by `MnO_(4)^(-)` ions = 2 mol
`:.` 1 mole of `SO_(3)^(2-)` ions is oxidized by `MnO_(4)^(-)` ions = 2/5 mol.