Which of the following statement is false for fuel cell?

Options

A. They are more efficient
B. They are free from pollution
C. They run till reactants are active
D. Fuel burned with `O_2`

Answer

To determine which statement is false regarding fuel cells, let's analyze the characteristics of fuel cells step by step.

### Step-by-Step Solution:

1. **Understanding Fuel Cells**:
Fuel cells convert chemical energy from fuels (like hydrogen) into electrical energy through electrochemical reactions. The most common type is the hydrogen-oxygen fuel cell.

**Hint**: Recall that fuel cells primarily use hydrogen and oxygen in their reactions.

2. **Reactions in Fuel Cells**:
- At the **anode**, hydrogen gas reacts with hydroxide ions (OH⁻) to produce water and electrons.
- At the **cathode**, oxygen gas reacts with water and electrons to produce hydroxide ions.

**Hint**: Remember the roles of anode and cathode in the electrochemical reactions.

3. **Net Reaction**:
The overall reaction in a hydrogen-oxygen fuel cell can be summarized as:
\[ 2H_2 + O_2 \rightarrow 2H_2O + \text{Energy} \]
This indicates that water is the main product, and energy is released.

**Hint**: Focus on the products of the reaction to understand the efficiency and pollution aspects.

4. **Efficiency and Pollution**:
- Fuel cells are considered efficient because the hydroxide ions used at the anode are regenerated at the cathode.
- The only byproduct of this reaction is water, which means fuel cells are environmentally friendly and free from pollution.

**Hint**: Think about what makes a process efficient and environmentally friendly.

5. **Evaluating the Statements**:
Now, let’s evaluate the given statements:
- **Statement A**: Fuel cells are more efficient. (True)
- **Statement B**: Fuel cells are free from pollution. (True)
- **Statement C**: Fuel cells run until the reactants are active. (True)
- **Statement D**: Fuel is burned with oxygen. (False)

**Hint**: Identify which statement does not align with the principles of how fuel cells operate.

6. **Conclusion**:
The false statement among the options is **Statement D**, which incorrectly suggests that fuel is burned with oxygen. In reality, fuel cells utilize hydroxide ions rather than burning fuel with oxygen.

**Final Answer**: The false statement is **D**: "Fuel is burned with oxygen."