The reaction showing endothermic nature and reduction of halogen is

Options

A. `F_(2)+½O_(2)toF_(2)O`
B. `Cl_(2)+O_(2)toCl_(2)O`
C. `F_(2)+H_(2)Oto2HF+½O_(2)`
D. none of the above

Answer

To solve the question regarding the endothermic nature and reduction of halogen, we will analyze the given reactions step by step.

### Step 1: Understanding Endothermic Reactions
An endothermic reaction is one that absorbs energy from its surroundings, usually in the form of heat. This means that the products of the reaction have higher energy than the reactants.

### Step 2: Analyzing the First Reaction
The first reaction given is:
\[ \text{F}_2 + \frac{1}{2} \text{O}_2 \rightarrow \text{F}_2\text{O} \]

- **Energy Requirement**: Fluorine (F2) and oxygen (O2) are stable molecules. When they combine to form fluorine oxide (F2O), energy is required. Therefore, this reaction is endothermic.

- **Oxidation State Change**: In this reaction, the oxidation state of fluorine changes from 0 (in F2) to -1 (in F2O). A decrease in oxidation state indicates that fluorine is being reduced.

### Conclusion for the First Reaction
This reaction is both endothermic and involves the reduction of halogen (fluorine).

### Step 3: Analyzing the Second Reaction
The second reaction is:
\[ \text{Cl}_2 + \frac{1}{2} \text{O}_2 \rightarrow \text{Cl}_2\text{O} \]

- **Energy Requirement**: Similar to the first reaction, chlorine (Cl2) and oxygen (O2) are also stable, and energy is required to form Cl2O. Hence, this reaction is also endothermic.

- **Oxidation State Change**: The oxidation state of chlorine changes from 0 (in Cl2) to +1 (in Cl2O). This indicates that chlorine is being oxidized, not reduced.

### Conclusion for the Second Reaction
This reaction is endothermic, but it does not involve the reduction of halogen. Therefore, it does not satisfy both conditions.

### Step 4: Analyzing the Third Reaction
The third reaction is:
\[ \text{F}_2 + \text{H}_2\text{O} \rightarrow 2\text{HF} + \frac{1}{2} \text{O}_2 \]

- **Energy Requirement**: This reaction is exothermic because it releases energy when fluorine reacts with water to form hydrofluoric acid (HF).

- **Oxidation State Change**: In this reaction, the oxidation state of fluorine changes from 0 (in F2) to -1 (in HF), indicating that fluorine is being reduced.

### Conclusion for the Third Reaction
Although this reaction involves the reduction of halogen, it is not endothermic.

### Final Answer
The only reaction that is both endothermic and involves the reduction of halogen is:
\[ \text{F}_2 + \frac{1}{2} \text{O}_2 \rightarrow \text{F}_2\text{O} \]