Minimum temperature to which a fuel other than a liquid in air must be heated in order to start self sustain combustion independent of the heating source.

• A. Auto Ignition Temperature
• B. Flash Point
• C. Fire Point
• D. Ignition Temperature

Answer: (D)

Self-ignition in air without any external heat source is defined by the autoignition temperature. It is the minimum temperature at which a material will spontaneously ignite when exposed to air, and the combustion can continue on its own once started. This differs from the other terms: flash point applies to liquids and is about vapors that can ignite only with an external ignition source; fire point is the temperature at which a flame can be sustained after ignition; and ignition temperature typically refers to the temperature needed to ignite in the presence of an external flame or spark. Since the scenario describes starting combustion without ongoing heat input, the autoignition temperature is the correct concept.