`KMnO_4` acts as an oxidising agent in acidic medium. The number of moles of `KMnO_4` that will be needed to react with one mole of sulphide ions in acidic solution as

Options

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

Answer

B

Explanation

`2KMnO_(4)+3H_(2)SO_(4)toK_(2)SO_(4)+2MnSO_(4)+3H_(2)O+5[O]`
`[MnO_(4)^(-)+8H^(+)+5e^(-)toMn^(2+)+4H_(2)O]xx2`
`[SO_(3)^(2-)+H_(2)OtoSO_(4)^(2-)+2H^(+)+2e^(-)]xx5`
`2MnO_(4)^(-)+6H^(+)+5SO_(3)^(2-)to2Mn^(2+)+5 SO_(4)^(2-)+3H_(2)O`
5 moles of sulphite ions react with =2 moles of `MnO_(4)^(-)`
So , 1 mole of sulphite ions react with `=(2)/(5)" moles of "MnO_(4)^(-)`.