Chemistry - Complete d-block Question with Solution | TestHub

The atomic numbers of the given elements are $\text{Cr}(24)$, $\text{Mn}(25)$, $\text{Co}(27)$, $\text{Cu}(29)$, and $\text{Zn}(30)$.

The observed electronic configurations are:
$\text{Cr}:[\text{Ar}]3d^{5}4s^1$
$\text{Mn}:[\text{Ar}]3d^{5}4s^2$
$\text{Co}:[\text{Ar}]3d^{7}4s^2$
$\text{Cu}:[\text{Ar}]3d^{10}4s^1$
$\text{Zn}:[\text{Ar}]3d^{10}4s^2$

Both $\text{Cr}$ and $\text{Mn}$ have exactly $5$ electrons in their $3d$ subshell, which corresponds to a half-filled $d$-orbital configuration.

Answer: Mn and Cr