Question

26 number
26. The number of d-electrons in $F{e}^{2+}\left(Z=26\right)$ is not equal to the number of electrons in which one of the following?
(1) p-electrons in Cl (Z = 17)
(2) d-electrons in Fe (Z = 26)
(3) p-electrons in Ne (Z = 10)
(4) s-electrons in Mg (Z = 12 )

Answer 1

Dear Student,

The configuration of electrons of the atoms are as below,

Fe = 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶ 4s² { for Z=26}
Fe²⁺ = ​ 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶

so we get retained d = 6-orbital
p-electron in Cl (Z=17) is 11(2p⁶3p⁵)
d-electron in Fe (Z=26) is 6(d⁶)
p-electron in Ne (Z=10) is 6(2p⁶)
s-electron in Mg (Z=12) is 6(1s²2s²3s²)

from the above analysis answer is Option (A) p-electron in Cl which does not equal with d-electron of Fe²⁺

Regards.