Chemistry - Complete d-block Question with Solution | TestHub

Electrons must be removed from the outermost orbital to form an ion.

The electronic configurations of the elements are as follows,

${}_{24}\mathrm{Cr}\to \left[\mathrm{Ar}\right]3 {\mathrm{d}}^{5}4{\mathrm{s}}^1; {\mathrm{Cr}}^{2+}\to \left[\mathrm{Ar}\right]3{\mathrm{d}}^4$

${}_{25}\mathrm{Mn}\to \left[\mathrm{Ar}\right]3{\mathrm{d}}^{5}4{\mathrm{s}}^2;{\mathrm{Mn}}^{+}\to \left[\mathrm{Ar}\right]3{\mathrm{d}}^5 4{\mathrm{s}}^1$

${}_{28}\mathrm{Ni}\to \left[\mathrm{Ar}\right]3{\mathrm{d}}^{8}4{\mathrm{s}}^2; {\mathrm{Ni}}^{2+}\to \left[\mathrm{Ar}\right]3{\mathrm{d}}^8$

${}_{23} \mathrm{V}\to \left[\mathrm{Ar}\right] 3{\mathrm{d}}^{3}4{\mathrm{s}}^2; {\mathrm{V}}^{+}\to \left[\mathrm{Ar}\right]3{\mathrm{d}}^{3}4{\mathrm{s}}^1$

Hence option B is the answer.