13. Electrons do not stay excited forever . They return to normal bu dropping down to lower energy levels . Since energy cannot be created or destroyed , the exited electron releases the absorbed ___ as __ energy.

Heat energy.

Explanation:

The exited electron releases the absorbed energy as heat energy that provides energy to electrons to move from one orbit to another orbit. The electron avails kinetic energy which provides motion in the electron when the energy is absorbed by the electron while on the other hand, electron releases energy which brings the electron into its original orbit. So we can say that the electrons releases energy in the form of heat and come back to its original place.