How is an endothermic reaction identified

An endothermic reaction is identified by noting the drop in temperature in the system.

Explanation:

An endothermic reaction occurs by absorbing heat energy from the environment( apparatus and solution). Once the energy in the surrounding reduces the temperature drops. The energy absorbed is used to form new bonds. The energy absorbed is directly proportional to the temperature drop.

An endothermic reaction absorbs heat from its surroundings.  

Explanation:

An example is the reaction of acetic acid with baking soda.

Three ways to tell if a reaction is endothermic:

elements make up everything, and they combine to make compounds.

the answer is c