Identify the incorrect statement with respect to `KMnO_4`

Options

A. Dark purple in colour
B. It is decolourised by oils
C. Paramagnetic in nature
D. The anion has tetrahedral structure

Answer

To solve the question, we need to evaluate each statement regarding KMnO₄ (potassium permanganate) and identify the incorrect one.

### Step-by-Step Solution:

1. **Evaluate Statement A: "Dark purple in color."**
- KMnO₄ is known for its deep purple color due to the presence of the permanganate ion (MnO₄⁻). This statement is **correct**.

2. **Evaluate Statement B: "It is decolorized by oils."**
- KMnO₄ is used in organic chemistry as an oxidizing agent and can decolorize in the presence of unsaturated hydrocarbons (oils). This is because the unsaturation reacts with KMnO₄, leading to a color change. This statement is **correct**.

3. **Evaluate Statement C: "Paramagnetic in nature."**
- To determine the magnetic properties, we need to check for unpaired electrons in the MnO₄⁻ ion. Manganese in KMnO₄ has an oxidation state of +7. In this state, all the 3d and 4s electrons are removed, resulting in no unpaired electrons. Therefore, KMnO₄ is **diamagnetic**, not paramagnetic. This statement is **incorrect**.

4. **Evaluate Statement D: "The anion has tetrahedral structure."**
- The MnO₄⁻ ion has a tetrahedral geometry due to sp³ hybridization of the manganese atom, which forms four sigma bonds with oxygen atoms. This statement is **correct**.

### Conclusion:
The incorrect statement with respect to KMnO₄ is **Option C: "Paramagnetic in nature."**

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