The total number of valency electrons present in ${\mathrm{SO}}_4^{-2}$ion

For representative elements. No of valency electrons of an atom = It's group number "O" and "S" belongs to VI A group. In case of anion add the number of units of negative charges to the valance electrons. Total number of valency electrons in ${\mathrm{SO}}_4^{-2}$= 1 x 6 + 4(6) +2 =32