Which element is essential for combustion and must be present in proper amounts?

Oxygen is essential for combustion because it is the oxidizing agent that reacts with fuel in a combustion process. For combustion to occur, a fuel must combine with oxygen, producing heat, light, and various combustion products, such as carbon dioxide and water. The presence of an adequate amount of oxygen is critical because if there’s too little, combustion may be incomplete, leading to the production of pollutants like carbon monoxide and soot. Therefore, maintaining the correct balance of oxygen is crucial for efficient and safe combustion in HVAC systems and other applications involving burning fuels.

While hydrogen, nitrogen, and carbon dioxide play roles in combustion and the broader context of combustion processes, they do not serve as the primary element required for the process. Hydrogen can act as a fuel, nitrogen is often considered an inert gas in combustion reactions, and carbon dioxide is a product of combustion rather than an element necessary for the process.