The correct answer is Carbon dioxide.Due to its physical properties, carbon dioxide is the only extinguishing gas that is also used in fire extinguishers and fire extinguishing devices.Carbon dioxide (CO2) is stored in extinguishers in the liquid phase.Important PointsA fire extinguisher is a device used to extinguish or control small fires, often in emergency situations.Fire extinguishing residues are generally non-toxic. There are a few general precautions you should take regardless of the type of fire extinguisher used, as some can irritate the skin.Carbon di-oxide vaporizes when released thereby smothering a fire by excluding the air (oxygen) needed for combustion.?