The hydrogen -like species `Li^(2+)` is in a spherically symmetric state `S_(1)` with one node. Upon absorbing light , the ion undergoes transition to a state `S_(2)`. The state `S_(2)` has one radial node and its energy is equal is to the ground state energy of the hydrogen atom.
Energy of the state `S_(1)` in units of the hydrogen atom ground state energy is

Options

A. `075`
B. `1.50`
C. `2.25`
D. `4.50`

Answer

C

Explanation

Energy in `S_1` state
`E = -(13.6 xx 3^2)/(2^2)`
`= -9/4 xx 13.6 eV`
`E_H = -13.6 eV` (ground state)
`E = -9/4 xx E_H = 2.25 E_H`