How many percent of air is composed of oxygen?

The composition of air is a fundamental concept in both environmental science and firefighting. Air is composed of several gases, with nitrogen making up about 78% and oxygen around 21%. This oxygen concentration is crucial for combustion processes, as fires require oxygen to burn. The presence of 21% oxygen allows for the maintenance of combustion and is significant in understanding fire behavior and fire suppression techniques.

Recognizing that other options propose incorrect percentages helps solidify the understanding of atmospheric composition and its implications in firefighting scenarios. This knowledge is essential for fire fighters to effectively manage fires and ensure safety in environments where oxygen levels are altered, such as in confined spaces or during certain firefighting measures.