Which gas can support combustion?

Oxygen is the gas that can support combustion. It is essential for the combustion process, as it serves as an oxidizer that reacts with flammable materials to produce heat and light. In the presence of a fuel source and sufficient heat, oxygen enables a fire to ignite and sustain itself. This property is critical in applications such as medical settings where oxygen is utilized for patient care, but it also necessitates stringent safety measures to prevent fire hazards.

On the other hand, helium and carbon dioxide do not support combustion. Helium is an inert gas that does not react with other substances, making it non-flammable, while carbon dioxide is a product of combustion and acts as a fire suppressant. When introduced into a fire, carbon dioxide displaces oxygen, effectively extinguishing the flames. Therefore, oxygen is the only gas listed that has the ability to support combustion, highlighting its vital role in both clinical and environmental contexts.