Hydrocarbons are ordered 
Hydrocarbons are ordered based on the "adiabatic" temperature at which this condition occurs. According to the NFPA rating system, the red number represents susceptibility to this condition. A common test for either the presence of hydrogen gas or oxygen gas involves introducing this condition. Atomic emission spectroscopy relies on the emission spectra produced when this is introduced to various metals, causing a red color for lithium and a yellow color for sodium; that's called its namesake "test". Robert Bunsen invented a lab device used to create it. For 10 points, name this form of ionized plasma that results from combustion reactions.
Hydrocarbons are ordered based on the "adiabatic" temperature at which this condition occurs.
fire [or flames; or combusting; or combustion; or being flammable; or being near a fire; or glowing splint; or burning splint; or really anything in that vicinity that has something to do with ignition]