In __________ combustion, a substance suddenly starts burning without any external cause.
Name one substance which undergoes spontaneous combustion (or burns in air at room temperature).
Fires in underground coal mines usually occur due to the :
(a) explosive combustion
(b) deliberate combustion
(c) spontaneous combustion
(d) rapid combustion
How is a spontaneous combustion different from a rapid combustion. Explain the difference in detail. [5 MARKS]