In `H_(2)-O_(2)` fuel cell, the reaction occurring at cathode is

Options

A. `2H_(2)O(l) rarr 2H_(2)(g)+O_(2)(g)`
B. `2H_(2)(g)+O_(2)(g) rarr 2H_(2)O(l)`
C. `CH_(4)(g)+O_(2)(g) rarr CO_(2)(g)+H_(2)O(l)`
D. `C(s)+O_(2)(g) rarr CO_(2)(g)`

Explanation

To determine the reaction occurring at the cathode of a hydrogen-oxygen (H2-O2) fuel cell, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Components of the Fuel Cell**:
- A hydrogen-oxygen fuel cell typically uses hydrogen (H2) as the fuel and oxygen (O2) as the oxidant.
- The cell consists of an anode and a cathode, separated by an electrolyte, often a KOH solution.

2. **Identify the Reactions at Each Electrode**:
- At the **anode**, hydrogen gas is oxidized. The reaction can be represented as:
\[ 2H_2 + 4OH^- \rightarrow 4H_2O + 4e^- \]
- At the **cathode**, oxygen gas is reduced. The reaction can be represented as:
\[ O_2 + 2H_2O + 4e^- \rightarrow 4OH^- \]

3. **Combine the Reactions**:
- The overall cell reaction combines the anode and cathode reactions:
\[ 2H_2 + O_2 \rightarrow 2H_2O \]
- This shows that hydrogen and oxygen react to form water.

4. **Focus on the Cathode Reaction**:
- The specific reaction occurring at the cathode involves oxygen, water, and electrons:
\[ O_2 + 2H_2O + 4e^- \rightarrow 4OH^- \]
- This indicates that oxygen is being reduced by gaining electrons and reacting with water to produce hydroxide ions.

5. **Conclusion**:
- Therefore, the reaction occurring at the cathode in a hydrogen-oxygen fuel cell is:
\[ O_2 + 2H_2O + 4e^- \rightarrow 4OH^- \]