Question

Sum of the paired electrons present in the orbital with $l=2$ in all the species $F{e}^{2+},C{o}^{2+}andN{i}^{+2}$ are:

• A. 9
• B. 12
• C. 6
• D. 15

Answer 1

The correct option is B 12

${}_{26}F{e}^{+2}\to 1s^2,2s^2,2p^6,3s^2,3p^6,4s^o,3d^6$
$l=2$ means d-subshell
No. of paired $e^{-}=2$
${}_{27}C{o}^{+2}\to 1s^2,2s^2,2p^6,3s^2,3p^6,4s^o,3d^7$
No of paired $e^{-}=4$
${}_{28}N{i}^{+2}\to 1s^2,2s^2,2p^6,3s^2,3p^6,4s^o,3d^8$
$\because$ No. of paired $e^{-}=6$
$\therefore$ Total paired $e^{-}$ = 2 + 4 + 6 = 12