Question

Which of the following is a polar molecule?
(a) $Xe{{F}_{3}}$
(b) $B{{F}_{3}}$
(c) $S{{F}_{3}}$
(d) $Si{{F}_{3}}$

Answer 1

Hint: Polar ,molecules are those whose net dipole moment of the bond pairs do not cancel each other and have some net dipole moment. Now find out that molecule whose net dipole moment is not zero and you will get your answer.

Complete step by step answer:
First of let’s discuss what is a polar molecule. By the polar molecule , we mean that molecule in which there is separation of the charges i.e. the positive and the negative charges and the molecule have net dipole. On the basis of the bonds which show the net dipole in a molecule, we can check whether the given molecule is polar or nonpolar and we can know about the bond pass and lone pairs in a molecule through the valence shell electron pair repulsion theory.

Now considering the statement as;
In option (a), through the VSEPR theory, we come to know that there are four bond pairs and two lone pairs of electrons and have square planar geometry and thus, the individual bond dipoles cancel each other and thus, this option is incorrect.
In option (b), through the VSEPR theory, we come to know that there are three bond pairs and no lone pair of electrons and has trigonal planar geometry and thus, the individual bond dipoles cancel each other and thus, this option is incorrect.
In option (c), through the VSEPR theory, we come to know that there are four bond pairs and one lone pair of electrons and has distorted tetrahedral geometry and thus, in this, the individual bond dipoles do not cancel each other and thus, this option is correct.
In option (d), through the VSEPR theory, we come to know that there are four bond pairs and no lone pairs of electrons and have tetrahedral geometry and thus, the individual bond dipoles cancel each other and thus, this option is incorrect.
So, thus, from the above given molecule only $S{{F}_{3}}$, is a polar molecule.
The correct option is option “C” .

Note: The polarity of the molecule depends on the presence of the electronegative atom in the molecule. More the electronegativity of the atom, more is the tendency of the atom to attract the shared pair of electrons towards itself and more is the polarity of the molecule and vice-versa.