Question

How many 'd' electrons in $C{u}^{+}$ can have the spin quantum $\left(\frac{-1}{2}\right)$?

Answer 1

${}_{29}C{u}^{+}\to \left[Ar\right]3d^{10}4s^0$
$\therefore$ Five 'd' electrons have $(+\frac{1}{2})$
and five 'd' electrons have $(-\frac{1}{2})$