Question

In which of the compounds does 'manganese' exhibit highest oxidation number?

• A. MnO₂
• B. Mn₃O₄
• C. K₂MnO₄
• D. MnSO₄

Hint:

Key Exam Tip:
Remember the common oxidation states of elements and the rules for assigning oxidation numbers. For manganese, known states include +2, +3, +4, +6, and +7. In $\text{K}_2\text{MnO}_4$, it's +6.

Answer 1

The Correct Option is C

Let's calculate the oxidation number of manganese in each compound:
MnO₂: Mn + 2(O) = 0 $\Rightarrow$ Mn + 2(-2) = 0 $\Rightarrow$ Mn = +4.
Mn₃O₄: $3(\text{Mn}) + 4(\text{O}) = 0 \Rightarrow 3(\text{Mn}) + 4(-2) = 0 \Rightarrow 3(\text{Mn}) = +8 \Rightarrow \text{Mn} = +8/3$. (This is an average; Mn is +2 and +3 in this mixed oxide).
K₂MnO₄: 2(K) + Mn + 4(O) = 0 $\Rightarrow$ 2(+1) + Mn + 4(-2) = 0 $\Rightarrow$ +2 + Mn - 8 = 0 $\Rightarrow$ Mn = +6.
MnSO₄: Mn + $(\text{SO}_4^{2-}) = 0$. The sulfate ion has a charge of -2. $\Rightarrow$ Mn + (-2) = 0 $\Rightarrow$ Mn = +2.
Comparing the oxidation states: +4, +8/3 (approx +2.67), +6, +2. The highest oxidation number is +6.
Final Answer: \(\boxed{C}\)