Chemistry - Complete d-block Question with Solution | TestHub

No. of unpaired electrons 
$\begin{array}{ccc}{}_{23}{\text{V}}^{2+}& {}_{18}\left[\text{Ar}\right]\mathrm{ 4}{\text{S}}^0\mathrm{ 3}{\text{d}}^3& = 3\\ {}_{24}{\text{Cr}}^{2+}& {}_{18}\left[\text{Ar}\right]\mathrm{ 4}{\text{S}}^0\mathrm{ 3}{\text{d}}^4& = 4\\ {}_{25}{\text{Mn}}^{2+}& {}_{18}\left[\text{Ar}\right]\mathrm{ 4}{\text{S}}^0\mathrm{ 3}{\text{d}}^5& = 5\\ {}_{26}{\text{Fe}}^{2+}& {}_{18}\left[\text{Ar}\right]\mathrm{ 4}{\text{S}}^0\mathrm{ 3}{\text{d}}^6& = 4\end{array}$

On moving left to right in the periodic table, ionic size decreases.

Sc shows only one oxidation state, and it is +3 but Mn shows variable oxidation state from +2 to +7.