what is spontaneous combustion class 8

Spontaneous combustion is a type of combustion that occurs by self-heating due to an increase in temperature caused by exothermic internal reactions within the substance, without the addition of heat from an external source. In other words, it is the bursting into flame of a mass of material as a result of chemical reactions within the substance, without the addition of heat from an external source. Some examples of spontaneous combustion include the burning of white phosphorus in air and the combustion of oily rags. Spontaneous combustion can occur when a substance having a relatively low ignition temperature begins to release heat, either by oxidation in the presence of air and moisture or bacterial fermentation that generates heat. The particular heat is unable to escape, and the temperature of the material increases.