Question

Wood or paper catches fire & emits heat & light but if we take coal for example then it emits heat & light but it becomes red hot instead of catching fire. Why. Explain with reason.

Answer 1

Combustible substances like coal does not catch fire till it reaches its ignition temperature. If the temperature is less than ignition temperature (455-600 ⁰C) then it wont catches fire. But on further heating it becomes red hot only. Whereas paper has ignition temperature of 233 ⁰C and its temperature is more than ignition temperature. So its called inflammable substance and it catches fire quickly and emits heat and light.