Which of the following has maximum number of paired electrons.

Options

A. `Cu^(+)`
B. `Fe^(3+)`
C. `Zr^(+)`
D. `Se^(+)`

Explanation

(1) `Cu_(29)^(+)-[Ar]_(18)3d^(10)` (2) `Fe_(26)^(+2)=[Ar]_(18)3d^(6)`
(3) `Zr_(40)^(+)=[Kr]_(36)5s^(1)3d^(2)` (4) `Se_(21)^(+)=[Ar]_(18)4s^(1)3d^(1)`