energy levels of the hydrogen-like boron ion B4-. Express the answer
in electrovolts and sketch the energy level diagram.
Calculate the energy of the photons corresponding to the lowest energy
spectral line that is emitted as a result of transitions down to the E2
energy level of this ion.
Calculate the energy of the lowest energy photon that B4+ could absorb,
if it is in its ground state. In no more than a couple of sentences,
explain the circumstances in which some hydrogen-like boron ions can
absorb photons of even lower energy.