Which gas is often used in medical procedures but is not flammable?

Nitrogen is indeed often used in medical procedures and is classified as a non-flammable gas. Its roles in healthcare include serving as a carrier gas in various applications and as a cryogenic agent for tissue preservation or during certain surgical procedures. Nitrogen is inert and does not support combustion, making it suitable for a range of medical uses without posing a fire risk.

In contrast, while carbon dioxide is also non-flammable and used medically, its primary applications are different compared to nitrogen. Oxygen, although crucial in medical settings to support respiration, is highly reactive and can promote combustion. Propane, on the other hand, is a flammable gas commonly used as a fuel source and is not appropriate for medical applications where non-flammability is a requirement. Thus, nitrogen stands out as the correct choice for a non-flammable gas utilized in medical procedures.