Which of the following best describes an excited state of an atom?

• A. A state in which the nucleus contains more neutrons than protons.
• B. A state in which all electrons are in their lowest possible energy levels.
• C. A state in which the atom has lost all of its electrons.
• D. A state in which one or more electrons occupy higher energy levels than the ground state.

Answer: (D)

Verified step by step guidance

1. Understand the concept of the ground state of an atom: it is the state where all electrons occupy the lowest possible energy levels available.
2. Recognize that an excited state occurs when one or more electrons absorb energy and move to higher energy levels than those in the ground state.
3. Note that the number of neutrons in the nucleus or the loss of all electrons does not define an excited state; these relate to isotopes and ionization, respectively.
4. Identify that the excited state specifically refers to the electron configuration being at a higher energy than the ground state, not changes in the nucleus or complete electron loss.
5. Conclude that the best description of an excited state is when one or more electrons occupy higher energy levels than the ground state.