Among the following the pair in which the two species are not isostructural is

Shape (structure) of a species can be ascertained on the basis of hybridization of its central atom, which in turn can be known by determining the number of hybrid bonds (H).(1) In SiF4 , Si undergoes SP3 hybridization and has zero lone-pairs ; Tetrahedral geometry.      In SF4 , S undergoes SP3d hybridization and has 1 lone-pair ; see-saw geometry.