The `p_(CO_(2))` level in the expired air under normal condition is approximately

Options

A. 46 mm of Hg
B. 100 mm of Hg
C. 32 mm of Hg
D. 116 mm of Hg

Answer

To determine the approximate level of \( p_{CO_2} \) in expired air under normal conditions, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Components of Expired Air**:
- Expired air contains carbon dioxide (CO2) as a waste product of cellular respiration.

2. **Normal Levels of \( p_{CO_2} \)**:
- Under normal physiological conditions, the partial pressure of carbon dioxide in the expired air is approximately 46 mm Hg.

3. **Comparison with Other Gases**:
- For context, the partial pressure of oxygen in the alveoli is about 104 mm Hg, while in the capillary blood it is around 40 mm Hg. This indicates that the levels of oxygen and carbon dioxide vary significantly in the respiratory process.

4. **Solubility of Gases**:
- It is important to note that carbon dioxide has a higher solubility in blood compared to oxygen, which affects the partial pressures of these gases in the respiratory system.

5. **Conclusion**:
- Based on the above information, we conclude that the \( p_{CO_2} \) level in expired air is approximately 46 mm Hg.

### Final Answer:
The \( p_{CO_2} \) level in the expired air under normal conditions is approximately **46 mm Hg**.

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