The powdered pyrolusite ore when fused with KOH in presence of air forms`"…..................."`.

Answer

To solve the question regarding the reaction of powdered pyrolusite ore (MnO2) when fused with KOH in the presence of air, we can follow these steps:

### Step 1: Identify the Reactants
The reactants in this reaction are:
- Pyrolusite ore, which is manganese dioxide (MnO2).
- Potassium hydroxide (KOH).
- Air (which provides oxygen).

### Step 2: Understand the Reaction Conditions
The reaction occurs when MnO2 is fused with KOH in the presence of air. The fusion process typically involves heating the mixture, which allows the reactants to interact.

### Step 3: Write the Reaction
When MnO2 is fused with KOH and exposed to air, it undergoes a reaction that can be represented as follows:

\[ 2 \text{MnO}_2 + 4 \text{KOH} + \text{O}_2 \rightarrow 2 \text{KMnO}_4 + 2 \text{H}_2\text{O} \]

### Step 4: Identify the Product
The main product of this reaction is potassium permanganate (KMnO4), which is a deep purple compound.

### Final Answer
The powdered pyrolusite ore when fused with KOH in the presence of air forms **potassium permanganate (KMnO4)**.

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