Question

The electronic configuration of transition element $\_{}^{{}^{\prime }}{X}_{}^{{}^{\prime }}$ is $[Ar]3d^5$ in its +3 oxidation state. What is its atomic number?

Answer 1

Answer: 26

$F{e}^{3+}=[Ar]3d^5$
${}_{26}^{}Fe=[Ar]3d^{6}4s^2$