What type of reaction is shown in this thermochemical equation? a b heat → c d

Explanation:

A chemical reaction in which heat is absorbed by reactants and hence energy of reactants is more than products is known as an endothermic reaction.

For example,   is an endothermic reaction.

Whereas when heat is released by reactants in a chemical reaction then energy of reactants is less than the energy of products. Therefore, this type of reaction is known as exothermic reaction.  

For example,   is an exothermic reaction.

Thus, we can conclude that the reaction a b heat → c d is endothermic reaction.

fe 55.85 g/mol and h2o 18.02 g/mol.

the answer is 75.0%.