Water is oxidised to oxygen by :

Options

A. `ClO_(2)`
B. `KMnO_(4)`
C. `H_(2)O_(2)`
D. Fluorine

Explanation

To determine which substance oxidizes water to produce oxygen, we can analyze the reactions of water with different substances.

### Step-by-Step Solution:

1. **Understanding Oxidation**:
- Oxidation involves an increase in the oxidation state of an element. In this case, we are interested in how water (H₂O) can be oxidized to produce oxygen (O₂).

2. **Identifying the Reaction**:
- The reaction of water with fluorine (F₂) is a well-known example. The balanced chemical reaction is:
\[ 2 \text{F}_2 + 2 \text{H}_2\text{O} \rightarrow 4 \text{HF} + \text{O}_2 \]
- Here, fluorine reacts with water to produce hydrofluoric acid (HF) and oxygen gas (O₂).

3. **Analyzing Oxidation States**:
- In water (H₂O), the oxidation state of hydrogen is +1 and that of oxygen is -2.
- In elemental oxygen (O₂), the oxidation state is 0.
- The change in oxidation state from -2 (in H₂O) to 0 (in O₂) indicates that oxygen is being oxidized.

4. **Comparing Other Substances**:
- When water reacts with ClO₂, the products are HClO₃ and HCl, with no oxygen gas evolved.
- When water reacts with H₂O₂ (hydrogen peroxide) or KMnO₄ (potassium permanganate), there is no evolution of oxygen gas.

5. **Conclusion**:
- The only substance that oxidizes water to produce oxygen is fluorine (F₂). Therefore, the answer to the question is:
- **Fluorine (F₂)**.