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

Explanation

` E_1 "for" He^+ = E_1 "for" H xx z^2 = E_1 xx 4`
` E_1 "for" Li^(2+) = E_1 "for" Hxx Z^2 =E_1 xx 9`
` therefore E_1 "for" Li^2+ = E_1 "for" He^+ xx 9//4`
` = 19 . 6 xx 10 ^(-18) xx 9//4`
` = 44.1xx 10 ^(-18) "J atom"^(-1)` .