The type of combustion in which any substance starts to burn of its own is called __________.
spontaneous
The process of burning of a substance in the presence of oxygen/air to produce heat and light is called __________ .
combustion
The lowest temperature at which a substance catches fire is called its _______ temperature.
ignition
A _______ is the region of combustion of gaseous vapours with the evolution of heat and light.
flame
The substances that undergo combustion are called __________ substances.
combustible