If the binding energy of the electron in a hydrogen atom is `13.6 eV`, the energy required to remove the electron from the first excited state of `Li^(++)` is

Options

A. 3.4 eV
B. 13.6 eV
C. 122.4 eV
D. 30.6 eV

Answer

D

Explanation

For the first excited state n = 2 and for lithium Z =3
`therefore` Energy for the first excited of lithium is
`E_Z = - (Z^2E_0)/(n^2) = (-(3)^2 xx13.6)/((2^2)) = -30.6 eV`
`therefore` Energy required to remove the electron = + 30.6 eV