Which substance is considered a primary component of uncontaminated air?

The primary component of uncontaminated air is nitrogen gas, represented by N2. In Earth's atmosphere, nitrogen makes up about 78% of the total volume, serving as a major but inert component that does not contribute to air pollution under normal conditions.

Uncontaminated air is characterized by the absence of significant levels of pollutants, including sulfur dioxide (SO2), ozone (O3), and nitrogen dioxide (NO2), which are typically produced by human activities and can lead to air quality issues. Nitrogen gas is not reactive under standard atmospheric conditions and plays a vital role in maintaining the overall composition of air without contributing to harmful effects. Hence, given its abundance and non-pollutive nature, nitrogen is the correct choice when identifying the primary component of clean air.