At 143 K, the reaction of ${\mathrm{XeF}}_4\text{ with }{\mathrm{O}}_2{\mathrm{F}}_2$ produces a xenon compound Y. The total
number of lone pair(s) of electrons present on the whole molecule of Y is ________

$X_e{F}_4+{\mathrm{O}}_2{F}_2\stackrel{143\mathrm{K}}{⟶}\underset{\left(Y\right)}{⟶Xe{F}_6}+{\mathrm{O}}_2$
In structure of XeF₆,one lone pair on Xe atom, three lone pairs on each F atom are present. Thus, total 19 lone pairs of electrons are present on whole molecule of Y.