Question

To an acidic solution of an anion, a few drops of $KMn{O}_4$ solution are added. Which of the following, if present, will not decolourise the $KMn{O}_4$ solution?

• A. $C{O}_3^{2-}$
• B. $N{O}_2^{\ominus }$
• C. $S^{2-}$
• D. ${Cl}^{\ominus }$

Answer 1

The correct option is A $C{O}_3^{2-}$

As we know, oxidation state of $C$ in $C{O}_3^{-2}$ is +4, which is maximum. So, it does not have any tendency to undergo oxidation and it will not able to reduce $KMn{O}_4$. Therefore, it will not decolourise the $KMn{O}_4$ solution.