Question

For an exothermic reaction,

• A. H of the product is less than that H of reactants
  where $H$ is the enthalpy of the product or reactant
• B. H of the product is more than that H of reactants
  where $H$ is the enthalpy of the product or reactant
• C. H of the product is equal to the H of reactants
  where $H$ is the enthalpy of the product or reactant
• D. $\Delta H=\Delta H\left(products\right)-\Delta H\left(reactants\right)$ is always positive

Answer 1

The correct option is A H of the product is less than that H of reactants

where $H$ is the enthalpy of the product or reactant
Exothermic reactions are chemical reactions which proceed with the evolution of heat energy.
In an exothermic reaction, the total enthalpy of the products is smaller than that of the reactants.
For example,
In a reaction, $P+Q\to R+S+q$
where q is the heat energy released
So, standard enthalpy change for this reaction is $\Delta H_{rxn}$ = $H\left(products\right)-H\left(reactants\right)=-q$