The hydrogen-like species $Li^{2+}$ is in a spherically symmetric state $S_1$ with one radial node. Upon absorbing light the ion undergoes transition to a state $S_2$ has one radial node and its energy is equal to the ground state energy of hydrogen atom. Energy of the state $S_1$ in units of the hydrogen atom ground state energy is

Question

$(a)\;0.75\qquad(b)\;1.50\qquad(c)\;2.25\qquad(d)\;4.50$