Explanation:
<em>When the electron changes levels, it decreases energy and the atom emits photons. The photon is emitted with the electron moving from a higher energy level to a lower energy level. The energy of the photon is the exact energy that is lost by the electron moving to its lower energy level.</em>
An exothermic reaction is a type of chemical reaction in which energy is released to the environment in form of heat or light. Endothermic reaction in the other hand is a chemical reaction where energy is taken from the surroundings and thus the surroundings end up with less energy than they started with. In this case; the above reaction is an Exothermic reaction (heat is being released to the surroundings).
The statement that best explains why heating a liquid affects its viscosity is that "The molecules move faster at higher temperatures and overcome attractions more easily."<span>. Remember that viscosity is a physical property of the fluids that measure the resistance (opposition) to flow and it, generally decreases, as the temperature increases and the intermolecular force decrease.</span>
