In a reaction:
\(MnO_4^- + 8H^+ + 5e^- \longrightarrow \underline{A} + H_2O\)
\(A\) stands for:
Answer & explanation
Correct answer: option 3
The correct answer is option 3. \(Mn^{2+}\).
To determine the oxidation state (\(A\)) of manganese (\(Mn\)) in the reaction:
\[MnO_4^- + 8H^+ + 5e^- \longrightarrow A + H_2O\]
We can use the following rules:
In permanganate (\(MnO_4^-\)), manganese is in the +7 oxidation state (\(+7\)).
In the product (\(A\)), manganese will undergo a reduction, gaining electrons.
Given that \(MnO_4^-\) is reduced to \(A\), the oxidation state of manganese in \(A\) should be less than +7. The only option that satisfies this criterion is: 3. \(Mn^{2+}\)