Question

In which of the following molecules/ion, all the bonds are not equal?

• A. $Xe{F}_4$
• B. ${BF}_4^{-}$
• C. $S{F}_4$
• D. $Si{F}_4$

Answer 1

Answer: (C)

$S{F}_4$

$S{F}_4$ has four bonded atoms and one lone pair. The five electron pairs around sulphur adopt trigonal bipyramidal geometry in which one position is occupied by a lone pair. This lone pair finds a position that minimizes the number of ${90}^0$ repulsions it has with bonding electron pairs. It occupies an equatorial position with two ${90}^0$ repulsions. The bonded electrons occupy the axial and equatorial positions. The axial S-F bonds are bent slightly away from the lone pair. Hence, all the bonds in $S{F}_4$ are not equivalent.