Question

Which of the following has maximum number of unpaired electrons?

• A. Zn
• B. ${Fe}^{2+}$
• C. ${Ni}^{3+}$
• D. ${Cu}^{+}$

Answer 1

The correct option is B ${Fe}^{2+}$

$Zn\left[Ar\right]4s^{2}3d^{10}\to 0$
$F{e}^{2+}\left[Ar\right]3d^6\to 4$
$N{i}^{3+}\left[Ar\right]3d^7\to 3$
$C{u}^{+}\left[Ar\right]3d^{10}\to 0$