In alkaline medium, the reduction of permanganate anion involves a gain of _____ electrons.
Correct Answer: 3
Solution and Explanation
The reduction of permanganate anion (MnO$_4^-$) in alkaline medium involves the following process:
\[ \text{MnO}_4^- \, (\text{oxidation state of Mn} = +7) \rightarrow \text{Mn}^{4+} \, (\text{oxidation state of Mn} = +4) \] The reduction from Mn$^{7+}$ to Mn$^{4+}$ involves the gain of 3 electrons, as the change in oxidation number is from +7 to +4.
Therefore, the reduction of permanganate anion involves the gain of 3 electrons.
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