½h2(g) + ½i2(g) → hi(g), δh = +6.2 kcal/mole 21.0 kcal/mole + c(s) + 2s(s) → cs2(l) what type of reaction is represented by the previous two examples?

Both the reactions are example of the endothermic reaction.

Explanation:

Endothermic reaction is a type of of chemical reaction in which energy is absorbed from the surrounding. The temperature of the surrounding decreases. The enthalpy of reaction is always positive

The above reaction is an example of endothermic reaction.

This reaction is also an endothermic reaction in which energy is being added on the reactant side which indicates that energy is absorbed during the reaction.

Exothermic reaction is a type of of chemical reaction in which energy is released into the surrounding. The temperature of the surrounding increases..The enthalpy of reaction is always negative

56 moles of   lieter in chemistry

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.