The ionization energy of `He^(+)` is `19.6 xx 10^(-18)J" atom"^(-1)`. The energy of the first stationary state of `Li^(+2)` will be:

Options

A. `84.2xx10^(-18)`J/atom
B. `44.10 xx 10^(-18)`J/atom
C. `63.2xx10^(-18)` J/atom
D. `21.2xx10^(-18)`J/atom

Answer

B

Explanation

`E_(1)" for "Li^(2+)=E_(1)" for "H xx Z^(2)=E_(1)" for "H xx 9`
`E_(1)" for "He^(+)=E_(1)" for "H xx Z_(He)^(2)=E_(1)" for "H xx 4`
or `E_(1)" for "Li^(2+) =(9)/(4) E_(1)" for "He^(+)=19.6 xx 10^(-18)` J/atom