Ionisation energy of `He^+` is `19.6 xx 10^-18 J "atom"^(-1)`. The energy of the first stationary state `(n = 1)` of `Li^( 2 +)` is.
A. `4.41xx10^(-16)"J atom"^(-1)`
B. `-4.41xx10^(-17)"J atom"^(-1)`
C. `-2.2 xx10^(-15)"J atom"^(-1)`
D. `8.82xx10^(-17)"J atom"^(-1)`