A doubly ionized lithium atom is hydrogen like with atomic number 3. Find the wavelength of the radiation required to excite the electron in `Li^(++)` from to the third Bohr orbit (ionization energy of the hydrogen atom equals 13.6 eV).

Answer

A, C, D

Explanation

In hydrogen atom,
`Delta E_1 = E_3 - E_1 = 12.1 eV`
`E prop Z^2`
`:. For Z = 3,`
`DeltaE_2 = ((3))^2 DeltaE_1 = ((3))^2 ((12.1))`
=108.9 Å
`:. Lambda = (12375)/(108.9) ~~ 113 Å.`