What is the electronic configuration of ${\mathrm{Cu}}^{2+}(Z=29)$  of least position 

 

${ }_{29}\mathrm{Cu}=\left[\mathrm{Ar}\right]3{\mathrm{d}}^{10}4{\mathrm{s}}^7,{\mathrm{Cu}}^{2+}=\left[\mathrm{Ar}\right]3{\mathrm{d}}^{9}4{\mathrm{s}}^0$

Ground state of ${\mathrm{Cu}}^{29}=1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^{6}3{\mathrm{d}}^{10}4{\mathrm{s}}^1$

${\mathrm{Cu}}^{2+}=1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^{6}3{\mathrm{d}}^9$