Question

The oxidation states not shown by Mn in the given reaction is:
$3MnO_4^{2-} + 4H^+ \rightarrow 2MnO_4^- + MnO_2 + 2H_2O$
A. +6
B. +2
C. +4
D. +7
E. +3
Choose the most appropriate answer from the options given below:

• A. D and E only
• B. B and D only
• C. A and B only
• D. B and E only

Answer 1

Answer: (D)

B and E only

Answer 2

Let's determine the oxidation states of Mn in the reactants and products:
In MnO$_4^{2-}$: Let $x$ be the oxidation state of Mn.
Then $x + 4(-2) = -2$, so $x = +6$.
In MnO$_4^-$: $x + 4(-2) = -1$, so $x = +7$.
In MnO$_2$: $x + 2(-2) = 0$, so $x = +4$.
The oxidation states of Mn in the reaction are +6, +7, and +4. Therefore, the oxidation states not shown are +2 and +3.