Electronic configurations of `Cu ( Z = 29)` is

Options

A. `1s^(2),2s^(2)2p^(6),3s^(2)3p^(6)3d^(9),4s^(2)`
B. `1s^(2),2s^(2)2p^(6),3s^(2)3p^(6)3d^(10),4s^(1)`
C. `1s^(2),2s^(2)2p^(6),3s^(2)3p^(6)4s^(2),4p^(6)`
D. `1s^(2),2s^(2)2p^(6),3s^(2)3p^(6)3d^(10)`

Answer

B

Explanation

3d subshell filled with 10 electrons (fully-filled) is more stable than that filled with 9 electrons. 1,4s electrons jumps into 3d subshell for more stability.