The number of d-electrons in Fe+2(Z -26)is not equal to the number of electrons in which one of the following

Electronic configuration of Fe2+ is [Ar]3d64s0∴ Number of electrons = 6Mg=1s22s22p63s2(6s electrons )It matches with the the 6d electrons of Fe2+Cl=1s22s22p63s23p5(11p electrons )It does not match with the 6d electrons of Fe2+Fe=[Ar]3d64s2(6d electrons )It matches with the 6d electrons of Fe2+Ne=1s22s22p6(6p electrons )It matches with the 6d electrons of Fe2+.Hence, Cl has 11p electrons which does not matches in number with 6d electrons of Fe2+