every reaction requires its reactants to have enough actvation energy in order to start the chemical reaction.sometimes, extra energy is provided in the form of heat. so the reactants take in heat from the surroundings and have enough energy to break old bonds and form new bonds. when they break old bonds they take in the heat energy provided right? then when they form new bonds they let out energy that is less than the heat energy provided hence some of the heat energy is actually taken in by the reactants right?that causes the temp drop as shown in the endothermic temp graph. just to clarify if my line of thought is correct, in this case the activation energy that the reactants possess come from the heat energy at room temperature as well as the heat energy from the heat source right? and that the amount of heat energy that reactants let out is much lesser than this energy combined, hence causing temp to drop to a minimum, am i right? the purpose of typing out this paragraph is to check if my theory has anything wrong in it, so please feel free to correct me if i am wrong!Thank You!