When$B{F}_3$ gas is passed through cryolite which of the change take place.

Cryollite $N{a}_{3}Al{F}_6$ is soluble in water. $B{F}_3$ gas is passed into the solution of cryolite the 
 stronger Lewis acid $B{F}_3$ takes up F- ions from cryolite precipitating insoluble $Al{F}_3.$ In this 
 process the products formed are $B{F}_4^{-}$ and $Al{F}_3.$ The hybridisation of boron changes from 
 $s{p}^2$ to $s{p}^3$ and that of aluminium $s{p}^3{d}^2$ in the complex changes during the formation of 
 ionic compound.