Question

Equivalent weight of $Mn{O}_4^{-}$ is equal to molecular weight, when it changes into new species $X$.

What is $X$? It is by oxidation or reduction.

• A. $Mn{O}_4^{2-}$ , Reduction
• B. $Mn{O}_2$, Oxidation
• C. $M{n}_2{O}_3$, Neither oxidation nor reduction
• D. None of these

Answer 1

The correct option is A $Mn{O}_4^{2-}$ , Reduction

Since equivalent weight is equal to molecular weight, the oxidation state has changed by one unit.

The highest oxidation state of Mn is +7 in $Mn{O}_4^{-}$. Hence the oxidation state decreases by one unit to +6.

$Mn{O}_4^{-1}⟶Mn{O}_4^{2-}$

This represents reduction.