A question about electrons and energy levels and light?

Question

When electrons move from the 4th energy level to the 2nd energy level, they emit visible light. Explain why the light emitted when an electron makes this move in a sodium atom is a different color than the light emitted by an electron moving from the 4th to 2nd level of a hydrogen atom.

Answer 1

A hydrogen atom contains only a single electron. A sodium atom has multiple electrons. The presence of electrons in other orbitals affects the energy for any particular transition.