What is the electronic configuration of `Cu^(2+)(Z=29)` of least position

Options

A. `[Ar]4s^(1)3d^(8)`
B. `[Ar]4s^(2)3d^(10)4p^(1)`
C. `[Ar]4s^(1)3d^(10)`
D. `[Ar]3d^(9)`

Answer

D

Explanation

`""_(29)Cu=[Ar]3d^(10)4s^(1),Cu^(2+)=[Ar]3d^(9).4s^(0).`
Ground state of `Cu^(29)=1s^(2)2s^(2)2p^(6)3s^(2)3p^(6)3d^(10)4s^(1)`
`Cu^(2+)=1s^(2),2s^(2)2p^(6),3s^(2)3p^(6)3d^(9)`.