Question

Which of the following species has a regular tetrahedral structure?
(Atomic number: $B=5,S=16,O=8,Xe=54)$

• A. $Xe{F}_4$
• B. $S{F}_4$
• C. $B{F}_4^{-}$
• D. $H_{2}O$

Answer 1

The correct option is C $B{F}_4^{-}$

The molecules assume different shapes based on the number of bond pairs/lone pairs in the valence shell of the central atom.

a) $Xe{F}_4$ has four bond pairs and two lone pairs. Hence, it has an octahedral geometry and square planar shaped.


b) $S{F}_4$ has four bond pairs and one lone pair. Hence, it has a trigonal bipyramidal geometry and see-saw shaped.



c) $B{F}_4^{-}$ has four bond pairs and hence, it has a regular tetrahedral structure.



d) $H_{2}O$ has two bond pairs and two lone pairs and hence, it has a tetrahedral geometry but the shape is bent.