Question

The number of d-electrons in ${Fe}^{2+}(Z=26)$ is not equal to that of the:

• A. p- electrons in Ne (at no = 10)
• B. s-electrons in Mg (at no. = 12)
• C. d - electrons in Fe
• D. p - electrons in $C{l}^{-}$ (at no. of Cl = 17)

Answer 1

The correct option is D p - electrons in $C{l}^{-}$ (at no. of Cl = 17)

$Z=26(6^{th}$ element in 3d series$)$
Electronic configuration is $\left[Ar\right]3d^{6}4s^2$
$\left(F{e}^{2+}\right)X^{+2}\left[Ar\right]3d^6$
No of d electrons $=6$
A) $1s^{2}2s^{2}2p^6\to 6$
B) 6
C) 6
D) $1s^{2}2s^{2}2p^{6}3s^{2}3p^5=11$ electrons.