Answer & Explanation
A chemical reaction in which involves the absorption of heat from the environment is called a Endothermic reaction.
Examples : Dissolving ammonium chloride in water, photosynthesis, melting ice cubes, mixing of potassium chloride with water,...
In the contrast, chemical reactions involving release of heat are known as exothermic reactions.
Examples : Combustion, coal is burnt, mix of CaO with water,...