Hydrogen-oxygen fuel cell are used in space-craft to supply

Options

A. Power for heat and light
B. Power for pressure
C. Oxygen
D. Water

Explanation

To answer the question regarding the use of hydrogen-oxygen fuel cells in spacecraft, we can break down the explanation into several steps:

### Step-by-Step Solution:

1. **Understanding the Fuel Cell**:
Hydrogen-oxygen fuel cells convert chemical energy from hydrogen and oxygen into electrical energy through electrochemical reactions. This process also produces water as a byproduct.

2. **Reactions in the Fuel Cell**:
- At the **cathode**, the reaction involves oxygen and water:
\[ O_2 + 2 H_2O + 4 e^- \rightarrow 4 OH^- \]
- At the **anode**, the reaction involves hydrogen and hydroxide ions:
\[ 2 H_2 + 4 OH^- \rightarrow 4 H_2O + 4 e^- \]

3. **Overall Cell Reaction**:
Combining the two half-reactions gives us the overall reaction:
\[ 2 H_2 + O_2 \rightarrow 2 H_2O \]
This shows that hydrogen and oxygen react to form water.

4. **Applications in Spacecraft**:
The energy produced from these reactions is harnessed to supply:
- **Power for heat and light**: Essential for maintaining a livable environment in spacecraft.
- **Power for pressure**: Helps in maintaining the structural integrity and functionality of the spacecraft.
- **Oxygen**: The reaction produces water, which can be split to provide breathable oxygen for astronauts.
- **Water**: The byproduct of the reaction is water, which is crucial for life support in space.

5. **Conclusion**:
Therefore, hydrogen-oxygen fuel cells are vital for supplying power, oxygen, and water in spacecraft, making them an essential component for long-duration missions.