Potassium permanganate is prepared by fusing pyrolusite with caustic potash in the presence of air or some oxidising agent which gives a green mass. The green mass is then extracted with water and treated with a current of `Cl_2` to form potassium permanganate. In the laboratory, it is prepared by oxidising a manganese (II) salt by peroxosulphate. It acts as an oxidising agent in neutral, alkaline or acidic solutions.
Write the disproportionation reaction of manganate ion in acidic medium.

Explanation

To write the disproportionation reaction of the manganate ion (MnO₄²⁻) in acidic medium, we need to follow these steps:

### Step 1: Identify the species involved
In acidic medium, the manganate ion (MnO₄²⁻) will undergo disproportionation. Disproportionation is a reaction where a single species is simultaneously oxidized and reduced.

### Step 2: Write the initial reaction
The manganate ion (MnO₄²⁻) will react with hydrogen ions (H⁺) in the acidic medium. The reaction can be represented as:
\[ \text{MnO}_4^{2-} + \text{H}^+ \rightarrow \text{MnO}_4^- + \text{MnO}_2 + \text{H}_2\text{O} \]
...