Which option correctly defines excitation?

• A. Excitation is when an electron is raised to a higher energy state
• B. Excitation is when an electron is removed from the atom
• C. Excitation is the emission of a photon
• D. Excitation is when a neutron is captured by the nucleus

Answer: (A)

Excitation means promoting an electron to a higher energy level within an atom or molecule by absorbing energy. The electron stays bound to the atom, just at a higher energy state, rather than being removed. This is why raising an electron to a higher energy state is the correct description. The other scenarios describe different processes: removing an electron is ionization, emitting a photon is the release of energy (often as the electron returns to a lower state after excitation), and neutron capture is a nuclear reaction involving the nucleus, not the electronic energy levels.