What is the approximate percentage and partial pressure of nitrogen (N₂) in the atmosphere at sea level?

The atmosphere at sea level is composed of various gases, with nitrogen being the most abundant. Nitrogen accounts for approximately 78% of the atmospheric composition. When considering atmospheric pressure at sea level, which is about 760 mmHg, the contribution of nitrogen to that pressure can be calculated using the percentage. By multiplying the atmospheric pressure by the fraction of nitrogen in the air (0.78), we arrive at a partial pressure of nitrogen approximately equal to 593 mmHg.

This understanding is crucial for applications in fields such as respiratory therapy and high-altitude medicine, where knowledge of gas compositions and their physiological effects is imperative. The other percentages and pressures provided in the other options do not accurately reflect nitrogen's correct composition in the atmosphere and thus do not represent the true data.