Question

define exothermic and endothermic reaction

Answer 1

exothermic reaction is nothing but the reaction in which heat is evolved,,,ND the reaction in which heat is liberated is called endothermic

Answer 2

Endothermic and exothermic reaction are the two types in the characteristic feature of chemical change.
Exothermic reaction
The reactions which are accompanied by the evolution of heat are called exothermic reaction.
Ex: C+O2= CO2+heat
CH4+2O2= CO2+2H2O+heat
C6H12O6+CO2= 6CO2+6H2O+heat
Endothermic reaction
The reactions which occur by the absorption of heat or energy are called endothermic reaction.
Ex:CaCO3+heat= CaO+CO2
2HgO+heat= 2Hg+O2
NH4Cl+heat= NH3+HCl