An electron in a hydrogen atom makes a transition from `n = 2` to `n = 1` and emits a photon. This photon strikes a doubly ionized lithium atom which was already in an excited state and completely removes the orbiting electron. The least quantum number for the excitted state of the lithium-ion for the process is

Options

A. `4`
B. `5`
C. `2`
D. `3`

Answer

A

Explanation

Energy of proton `=13.6-3.4=10.2eV`
For removal of electron
`10.2eVgt13.6(z^(2))/(n^(2))`
`n^(2)gt13.69/10.2`
so minimum value o `n=4`