Question

what is the source of energy that is absorbed by the electrons to move from the ground state to excited state?

Answer 1

I think an atom changes from a ground state to an excited state by taking on energy from its surroundings in a process called absorption. The electron absorbs the energy and jumps to a higher energy level. In the reverse process, emission, the electron returns to the ground state by releasing the extra energy it absorbed.

I hope this help you!:)