4.14 g of pure lead was dissolved in nitric acid and was made to react with  ${\text{HCl,\hspace{0.17em}\hspace{0.17em}Cl}}_{\text{2}}$ and  ${\text{NH}}_{\text{4}}\text{Cl}$ to convert lead completely into  ${\left({\text{NH}}_{\text{4}}\right)}_{\text{2}}{\text{PbCl}}_{\text{6}}\text{.}$ However, only 2.28 g of ${\left({\text{NH}}_{\text{4}}\right)}_{\text{2}}{\text{PbCl}}_{\text{6}}$  was actually produced. The percentage yield of the product is. (Atomic wt. of Pb = 207)