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

Answer

A, B, D

Explanation

IE of an ion = IE of H atom `xx Z^(2)`
IE of H atom = `(IE of an ion)/(Z^(2))= (IE of an He^(o+))/(Z^(2))`
`= (19.6 xx 10^(-18))/(4) J = 4.9 xx 10^(-18) J`
`IE of Li^(2+) = 4.9 xx 10^(-18) J xx 3^(2) = 4.41 xx 10^(-17) J`