What can nitrogen combine with to form NOx?

Nitrogen can combine with oxygen to form nitrogen oxides, commonly referred to as NOx. This reaction typically occurs at high temperatures, such as those found in combustion processes, where nitrogen and oxygen from the air react to create various nitrogen oxides, including nitric oxide (NO) and nitrogen dioxide (NO2).

The formation of NOx is significant because these compounds are pollutants that can contribute to smog and acid rain, as well as have negative health effects on humans. Understanding this process is crucial in managing emissions from gas heating systems and ensuring compliance with environmental regulations.

The other options do not facilitate the formation of NOx. Hydrogen does not combine with nitrogen in a way that produces nitrogen oxides. Carbon monoxide, while it is a product of incomplete combustion, does not lead to the generation of NOx. Helium is an inert noble gas and does not participate in chemical reactions to form nitrogen compounds. Therefore, oxygen is the essential element that combines with nitrogen to create NOx, and recognizing this relationship is vital for HVAC professionals when considering combustion efficiency and emissions control.