Question

The diagram to the right shows the lowest four energy levels for an electron in a hypothetical atom. The electron is excited to the −1 eV level of the atom and transitions to the lowest energy state by emitting only two photons. Which of the following energies could not belong to either of the photons?

(A) 2 eV

(B) 4 eV

(C) 5 eV

(D) 6 eV

(E) 9 eV

Answer 1

The correct option is: (B) 4 eV

Explanation:

To transition to the –12eV state with only two photon emissions, the only options are for the electron to make the following transitions: –1eV → – 3eV → –12eV giving us photons of energy 2eV and 9eV or –1eV → – 7 eV → – 12eV giving photons of energy 6eV and 5eV . This means that the 4 eV photon is not possible with only two transitions.