The correct option is A 1
Endothermic reactions are the chemical reactions which proceed with the absorption of heat energy.
Consider the reaction A+B+q→C+D.
Here, q is the heat energy absorbed during this exothermic reaction.
The enthalpy change for this reaction is ΔHrxn=Hproducts−Hreactants=+q
Positive sign indicates that heat is absorbed in the reaction.
Hence, Hreactants+q=Hproducts
Thus, in an endothermic reaction, the total enthalpy of reactant is smaller than that of products.