Three energy levels of an atom are shown above. Atoms in the state can spontaneously emit photons having which of the following energies?

### Select an Answer

4 eV only

7 eV only

3 eV and 4 eV only

3 eV and 7 eV only

3 eV, 4 eV, 7 eV

### View Correct Answer

The correct answer is eV only. According to the energy level diagram, atoms in the state have an energy of eV above the ground state . Atoms can only emit photons spontaneously when they drop to a lower energy level. According to conservation of energy, the energy of the photon will equal the difference in energy of the two atomic states. For atoms in state, the only lower energy level available is the ground state. So the only photon energy possible is equal to the difference in energy of these two states, eV $-$ $0$eV, which is equal to eV.