To an acidic solution of anion a few drops of acidified `KMnO_(4)` are added. Which one of the following anions , if present wil not decolourise the `KMnO_(4)` solutions ?

Options

A. `I^(-)`
B. `CO_(3)^(2-)`
C. `S^(2-)`
D. `NO_(2)^(-)`

Answer

B

Explanation

`I^(-), S^(2), NO_(2)^(-) and Cl^(-)` decolourise `KMnO_(4)` solution in acidic medium. The chemical equation are given below :
`2MnO_(4)^(-) + 16H^(+) + 10X^(-) to 2Mn^(2+) + 8H_(2)O +M 5X_(2) (X^(-) = Cl^(-) , I^(-))`
`2MnO_(4)^(-) + 16H^(+) + 5s^(2-) to 2Mm^(2+) +8 H_(2)O + 5S`
`2MnO_(4)^(-) + 6H^(+) + 5NO_(2)^(-) to 2Mn^(2+) + 3H_(2)O + 3H_(2)O + 5NO_(3)^(-)`