Which of the following is considered a non-flammable medical gas?

Nitrogen is classified as a non-flammable medical gas. It is an inert gas that does not support combustion or contribute to fire hazards, making it safe for use in various medical applications. In medical settings, nitrogen is often used to create a controlled environment, assist in cryotherapy, and provide a means of powering certain medical devices.

Oxygen, while essential for respiration in medical settings, is not considered non-flammable because it supports combustion. Hydrogen is highly flammable and poses significant fire and explosion risks. Acetylene is also flammable and is primarily used as a fuel gas in welding and cutting applications rather than in medical environments.