`KO_2 or Na_2 O_2` is used in submarines or space capsules because

Options

A. it absorbs `CO_2`
B. it releases `O_2`
C. it produces corresponding carbonate on reaction with `CO_2`
D. None of these.

Answer

To answer the question about why KO₂ (potassium superoxide) or Na₂O₂ (sodium peroxide) is used in submarines or space capsules, we can break down the reasoning step by step.

### Step-by-Step Solution:

1. **Understanding the Function of KO₂ and Na₂O₂**:
- KO₂ and Na₂O₂ are both peroxides that can react with carbon dioxide (CO₂) and release oxygen (O₂). This is crucial in enclosed environments like submarines and space capsules where the air supply is limited.

2. **Reaction with CO₂**:
- When KO₂ or Na₂O₂ comes into contact with CO₂, they undergo a chemical reaction that absorbs CO₂ from the air. This is important because CO₂ levels need to be controlled to maintain a breathable atmosphere.

3. **Release of Oxygen**:
- In addition to absorbing CO₂, these compounds also release O₂ as a byproduct of their reaction. This is essential for providing a continuous supply of oxygen for the crew in submarines or space capsules.

4. **Production of Carbonates**:
- The reaction of KO₂ or Na₂O₂ with CO₂ can also lead to the formation of corresponding carbonates. However, the primary function in the context of submarines and space capsules is the absorption of CO₂ and the release of O₂.

5. **Conclusion**:
- Therefore, the correct answer to the question is that KO₂ or Na₂O₂ is used in submarines or space capsules because they absorb CO₂ and release O₂.

### Final Answer:
KO₂ or Na₂O₂ is used in submarines or space capsules because they absorb CO₂ and release O₂.