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.