Answer:
Heat is taken in from the surrounding environment.
Step-by-step explanation:
There are two groups of reactions endothermic and exothermic.
Endothermic reactions have a positive ΔH. This means that in order for the reaction to take place, a certain amount of energy is needed to break and form the bonds between the newly formed compound/s.
Exothermic reactions have a negative ΔH. This means that when the reaction takes place, there is still energy "left over" after all the bonds have been formed, this leads to the expulsion of that energy into the environment.