Which of the following species contains manganese with the highest oxidation number?

• A. MnO_4^-
• B. Mn^{2+}
• C. MnO_2
• D. MnSO_4

Answer: (A)

Verified step by step guidance

1. Identify the oxidation state of manganese in each species by using the known oxidation states of the other elements and the overall charge of the species.
2. For \( \text{Mn}^{2+} \), the oxidation state of manganese is simply +2 because it is a monoatomic ion with a charge of +2.
3. For \( \text{MnO}_2 \), assign oxygen an oxidation state of -2 (a common oxidation state for oxygen). Since there are two oxygens, the total oxidation state contributed by oxygen is \( 2 \times (-2) = -4 \). Let the oxidation state of manganese be \( x \). The compound is neutral, so set up the equation: \( x + (-4) = 0 \). Solve for \( x \).
4. For \( \text{MnSO}_4 \), recognize that sulfate ion \( \text{SO}_4^{2-} \) has a charge of -2. Since the compound is neutral, manganese must balance this charge. Let the oxidation state of manganese be \( x \). Set up the equation: \( x + (-2) = 0 \). Solve for \( x \).
5. For \( \text{MnO}_4^- \), assign oxygen an oxidation state of -2. With four oxygens, total oxygen charge is \( 4 \times (-2) = -8 \). The overall charge of the ion is -1. Let the oxidation state of manganese be \( x \). Set up the equation: \( x + (-8) = -1 \). Solve for \( x \). Compare all manganese oxidation states found and identify which is the highest.