Question

state what kind of chemical reaction in combustion of coal in air

Answer 1

It is an exothermic reaction because during this process a large amount of heat and energy is released

Answer 2

Burning coal is a chemical change called combustion. A combustion is the chemical reaction (redox reaction) of coal with oxygen O2. It is exothermic, which means it releases energy : hence the heat.

Burning coal is in fact not one type of combustion, but several types of combustion in competition producing CO2 and water, and other compounds such as small hydrocarbons and carbon monoxide.