The group 14 elements A and B have the first ionisation enthalpy values of 708 and 715 kJ mol^-1 respectively. The above values are lowest among…

The group $\displaystyle 14$ elements A and B have the first ionisation enthalpy values of $\displaystyle 708$ and $\displaystyle 715 \mathrm{~kJ} \mathrm{~mol}^{-1}$ respectively. The above values are lowest among their group members. The nature of their ions $\displaystyle \mathrm{A}^{2+}$ and $\displaystyle \mathrm{B}^{4+}$ respectively is