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

The Correct Option is D

Let's determine the various oxidation states of manganese (Mn) in the given reaction and identify which states are not present.

The reaction is: 

\(3MnO_4^{2-} + 4H^+ \rightarrow 2MnO_4^- + MnO_2 + 2H_2O\)

We need to identify the oxidation states of Mn in each compound:

1. \(MnO_4^{2-}\): Oxygen typically has an oxidation state of -2. Therefore, for \(MnO_4^{2-}\), let the oxidation state of Mn be \( x \).

x + 4(-2) = -2

1. Solving gives \(x = +6\).
2. \(MnO_4^{-}\): Again, oxygen is -2, so let the oxidation state of Mn be \( y \).

y + 4(-2) = -1

1. Solving gives \(y = +7\).
2. \(MnO_2\): Here, with oxygen being -2, the oxidation state of Mn (\( z \)) in \(MnO_2\) is:

z + 2(-2) = 0

1. Solving gives \(z = +4\).

The oxidation states of Mn present in the reaction are +6, +7, and +4.

Now, let's look at the options:

1. +6 is present, so options including A are incorrect.
2. +7 is present, so options including D are incorrect.
3. +4 is present, so options including C are incorrect.
4. +2 is not present, making option B correct.
5. +3 is not present, making option E correct.

Thus, the oxidation states not shown by Mn in the reaction are +2 and +3.

The correct answer is: B and E only.