Which of the elements possess only one electron in 5d-orbital?

Options

A. `""^(69)Tm , ""^(61)Pm`
B. `""^(50)Pr , ""^(71) Lu`
C. `""^(57) La , ""^(61) Pm`
D. `""^(57)La , ""^(71) Lu`

Answer

D

Explanation

`""^(57)La` and `""^(71)Lu` have `d^1` electronic configuration
Electronic configuration of `""^(57)La = overset(54)([Xe]) 5d^(1) 6s^(2)`
Electronic configuration of `""^(71)Lu = overset(54)([Xe])4f^(14) 5d^1`