Question

which of the following has zero dipolemoment? a) ClF b) PCl3 c) SiF4 d) CFCl3

Answer 1

Answer:- c) $SiF_4$

Explanations:- Dipole moment is the measurement of polarity of a bond. If the molecule has some net dipole moment then it means the molecule is over all polar.

The geometry of the molecule is important here. If the molecule is symmetrical then it's dipole moment is zero and the molecule is non polar. For example, carbon dioxide (O=C=O) has two polar O=C bonds but since the directions are opposite for each other, the net dipole moment is zero and so the molecule is non polar.

ClF is a linear molecule. F is more electron negative than Cl, so the direction of dipole moment is from Cl to F and the molecule is polar.

$PCl_3$ is trigonal pyramidal means it is not asymmetrical and so it has  some net dipole moment that makes it polar.

$CFCl_3$ has is tetrahedral but all the bonds are not same means the dipole moment of C-F bond is not exactly same as the dipole moment of C-Cl bond. So, the molecule has some net dipole moment and so it is polar.

$SiF_4$ is a tetrahedral molecule with all same bonds and because of this it's net dipole moment is zero and the molecule is non polar.

So, the correct choice is c)  $SiF_4$ .