To an aqueous solution containing anions a few drops of acidified KMnO4 are added. Which one of the following anions, if present will not decolourise the KMnO4 solution?

Question

To an aqueous solution containing anions a few drops of acidified KMnO4 are added. Which one of the following anions, if present will not decolourise the KMnO4 solution? (A)  I-  (B)  CO32-  (C)  S2-  (D)  NO2-

Tardigrade Admin · Accepted Answer

In CO32-, C is present in its highest oxidation state, ie, +4 state, so its further oxidation is not possible, it only undergoes reduction. Acidified KMnO4 is a strong oxidizing agent, but it cannot oxidize CO32- . Hence, it will not be decolorized by CO32- .

Q. To an aqueous solution containing anions a few drops of acidified $K M n O_{4}$ are added. Which one of the following anions, if present will not decolourise the $K M n O_{4}$ solution?

$I^{-}$

$C O_{3}^{2 -}$

$S^{2 -}$

$N O_{2 -}$

$C l^{-}$

In $C O_{3}^{2 -},$ C is present in its highest oxidation state, ie, +4 state, so its further oxidation is not possible, it only undergoes reduction. Acidified $K M n O_{4}$ is a strong oxidizing agent, but it cannot oxidize $C O_{3}^{2 -}$ . Hence, it will not be decolorized by $C O_{3}^{2 -}$ .

Q. To an aqueous solution containing anions a few drops of acidified KMnO4​ are added. Which one of the following anions, if present will not decolourise the KMnO4​ solution?

I−

CO32−​

S2−

NO2−​

Cl−

In CO32−​, C is present in its highest oxidation state, ie, +4 state, so its further oxidation is not possible, it only undergoes reduction. Acidified KMnO4​ is a strong oxidizing agent, but it cannot oxidize CO32−​ . Hence, it will not be decolorized by CO32−​ .