This is due todaystudy the graph below to answer the question. reaction a is an exothermic process and reaction b is an endothermic process because a. the enthalpy change of reaction a is lower than that of reaction b. b. δh is positive for reaction a and δh is negative for reaction b. c. the energy of activation of reaction a is lower than that of reaction b. d. δh is negative for reaction a and δh is positive for reaction b.

Answer is: D. ΔH is negative for reaction A and ΔH is positive for reaction B.

There are two types of thermochemical reactions:  

1) endothermic reaction (chemical reaction that absorbs more energy than it releases).

For example, ΔH(reaction) = 150 kJ/mol; this is endothermic reaction.

2) exothermic reaction (chemical reaction that releases more energy than it absorbs).

For example, ΔH(reaction) = -225 kJ/mol; this is exothermic reaction.

the change in enthalpy = the total bonding energy for the products of a reaction - the bonding energy of the reactants.