Heat is adsorption in physical adsorption is

The heats of adsorption in physisorption or physical adsorption lies in the range of 10−40 kJ/mol. It is less as compared to chemisorption as there is no chemical reaction involved in it.

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.