What is the approximate partial pressure of oxygen at 25,000 ft (barometric pressure ≈ 282 mmHg)?

To determine the approximate partial pressure of oxygen at a given altitude, we can use the concept of atmospheric pressure and the percentage of oxygen in the atmosphere. At sea level, atmospheric pressure is approximately 760 mmHg, and oxygen constitutes about 21% of the atmosphere.

At 25,000 feet, where the barometric pressure is given as approximately 282 mmHg, the partial pressure of oxygen has to be calculated as follows:

1. Calculate the partial pressure of oxygen by multiplying the barometric pressure by the fraction of oxygen in the atmosphere:

[

\text{Partial Pressure of O}_2 = \text{Barometric Pressure} \times 0.21

]

2. Substituting the values:

[

\text{Partial Pressure of O}_2 = 282 \text{ mmHg} \times 0.21 \approx 59.22 \text{ mmHg}

]

This results in a partial pressure of approximately 59 mmHg, which aligns with the selected answer.

Understanding this calculation is crucial in fields such as medicine and aviation, where knowledge of oxygen levels at various altitudes can significantly impact patient care, flight safety, and performance. The approximate partial