Which compound amongst the following gas the highest oxidation number of Mn?
`KMnO_(4), K_(2)MnO_(2), MnO_(2) and Mn_(2)O_(3)`

Options

A. (A) `KMnO_(4)`
B. (B) `K_(2)MnO_(4)`
C. (C) `MnO_(2)`
D. (D) `Mn_(2)O_(3)`

Explanation

To determine which compound has the highest oxidation number of manganese (Mn) among the given options, we will calculate the oxidation number of Mn in each compound step by step.

### Step 1: Calculate the oxidation number of Mn in KMnO₄
1. The formula for potassium permanganate is KMnO₄.
2. The oxidation number of potassium (K) is +1.
3. The oxidation number of oxygen (O) is -2.
4. Let the oxidation number of Mn be \( x \).
5. The overall charge of the compound is neutral (0), so we can set up the equation:
\[ +1 + x + 4(-2) = 0 \]
6. Simplifying this gives:
\[ +1 + x - 8 = 0 \implies x - 7 = 0 \implies x = +7 \]

### Step 2: Calculate the oxidation number of Mn in K₂MnO₂
1. The formula for potassium manganate is K₂MnO₂.
2. The oxidation number of potassium (K) is +1, and there are 2 potassium atoms, so:
\[ 2(+1) = +2 \]
3. The oxidation number of oxygen (O) is -2, and there are 2 oxygen atoms, so:
\[ 2(-2) = -4 \]
4. Let the oxidation number of Mn be \( x \).
5. Setting up the equation:
\[ +2 + x + (-4) = 0 \]
6. Simplifying this gives:
\[ x - 2 = 0 \implies x = +2 \]

### Step 3: Calculate the oxidation number of Mn in MnO₂
1. The formula for manganese dioxide is MnO₂.
2. The oxidation number of oxygen (O) is -2, and there are 2 oxygen atoms, so:
\[ 2(-2) = -4 \]
3. Let the oxidation number of Mn be \( x \).
4. Setting up the equation:
\[ x + 2(-2) = 0 \]
5. Simplifying this gives:
\[ x - 4 = 0 \implies x = +4 \]

### Step 4: Calculate the oxidation number of Mn in Mn₂O₃
1. The formula for manganese(III) oxide is Mn₂O₃.
2. The oxidation number of oxygen (O) is -2, and there are 3 oxygen atoms, so:
\[ 3(-2) = -6 \]
3. Let the oxidation number of Mn be \( x \), and since there are 2 manganese atoms, we have:
\[ 2x + (-6) = 0 \]
4. Simplifying this gives:
\[ 2x - 6 = 0 \implies 2x = 6 \implies x = +3 \]

### Summary of Oxidation Numbers
- KMnO₄: +7
- K₂MnO₂: +2
- MnO₂: +4
- Mn₂O₃: +3

### Conclusion
The compound with the highest oxidation number of Mn is **KMnO₄** with an oxidation number of +7.

### Final Answer
**A. KMnO₄**