Question

what happens when an electron transitions from a higher to a lower energy level?
a photon is emitted.
the atom becomes ionized.
no energy change occurs.
a photon is absorbed.

Explanation:

When an electron moves from a higher - energy level to a lower - energy level, it loses energy. This energy is released in the form of a photon. Ionization occurs when an electron is completely removed from an atom. There is an energy change when an electron transitions between levels, and absorption of a photon occurs when an electron moves from a lower to a higher energy level.

Answer:

A. A photon is emitted