The total number of valency electrons in ${{\mathrm{PO}}_4}^{3-}$ ion is

Phosphorus is in group V (A) so it has 5 valance electrons oxygen is in group VI (A) so it has 6 valance electrons, it also has 3- charge so for each charge we need to add 1 valance electrons therefore by adding up total valance electron we have,

$\begin{array}{rl} & {\mathrm{PO}}_4^{3-}\\ & 5+6\times 4+3=32\end{array}$

so, the total no, of valency electron in ${\mathrm{PO}}_4^{3-}$ ion is 32.

Hence, the correct option is option (A) 32.