Find the wavelength of radiation required to excite an electron in the ground levelll of `Li^(2+) (z = 3)` in the third energy level

Explanation

For `Li^(2+)` , transition occures from `n_(1)` = to `n_(2) = 3 `
`:. barv = RZ^(2)[(1)/(n_(1)^(2)) - (1)/(n_(2)^(2))] ["for" Li^(2+),Z = 3]`
`bar v = 109667 xx 3^(2) [(1)/(1^(2)) - (1)/(3^(2))]`
`bar v = 8.77 xx 10^(7)m^(-1)`
`or lambda = (1)/(bar v) = 113.9 Å`