Question

Which of the following is a polar molecule?
(A)- $\text{B}{\text{F}}_{\text{3}}$
(B)- $\text{S}{\text{F}}_{\text{4}}$
(C)- $\text{Si}{\text{F}}_{\text{4}}$
(D)- $\text{Xe}{\text{F}}_{\text{4}}$

Answer 1

Hint:. Those molecules whose dipole moment is not zero is polar in nature and whenever distortion of shape takes place from original geometry, non – planar structure and presence of unbalanced electronic structure is observed then there polarity is also present.

Complete step by step answer:
Here is the complete explanation of above given molecules:
-In option (A) $\text{B}{\text{F}}_{\text{3}}$ is given, in which three bond pair of electrons are present and hybridization of central atom i.e. Boron is $\text{s}{\text{p}}^{\text{2}}$ whose structure is trigonal planar and due to which its dipole moment is zero. So, $\text{B}{\text{F}}_{\text{3}}$ is a non - polar molecule.
-In option (B) $\text{S}{\text{F}}_{\text{4}}$ is given, in which four bond pair of electrons and one lone pair of electrons are present and hybridization of central atom i.e. Sulphur is $\text{s}{\text{p}}^{\text{3}}\text{d}$ whose structure is like see -saw and due to distorted structure its dipole moment is not zero. So, $\text{S}{\text{F}}_{\text{4}}$ is a polar molecule.
-In option (C) $\text{Si}{\text{F}}_{\text{4}}$ is given, in which four bond pair of electrons are present and hybridization of central atom i.e. Silicon is $\text{s}{\text{p}}^3$ whose structure is tetrahedral and due to regular geometry its dipole moment is zero. So, $\text{Si}{\text{F}}_{\text{4}}$ is a non - polar molecule.
-In option (D) $\text{Xe}{\text{F}}_{\text{4}}$ is given, in which four bond pair of electrons & two lone pair of electrons are present and hybridization of central atom i.e. Xenon is $\text{s}{\text{p}}^{\text{3}}{\text{d}}^{\text{2}}$ whose structure is square planar and due to planar structure its dipole moment is zero. So, $\text{Xe}{\text{F}}_{\text{4}}$ is a non - polar molecule.
So, the correct answer is “Option B”.

Note: Here some of you may think that $\text{Xe}{\text{F}}_{\text{4}}$ is also polar in nature because it is showing different structure (square planar) from the geometry (octahedral), but here structure is also planar that’s why it is non – polar.