Exothermic reactions are accompanied by the evolution of heat. It means that enthalpy of the reactants is more than the enthalpy of the products i.e.
Hr > Hp
But
State with reason whether the work is done by the system on the surroundings or on the system by the surroundings if the following change occurs at constant pressure:
What is the enthalpy of formation of the most stable form of an element in its standard state?