The polar molecule among following isCarbon tetrachlorideCo2Ch2cl2EthenePleas e tell what are ways to identify polar and non polar molecule with respect to their dipole momenta

What factor is used to decide the polarity of a molecule:Polarity/ non polarity of a molecule can be decided only by the net dipole moment of the molecule.

What is dipole moment: Dipole moment is due to the separation of the negative postive charges. And is mathematically decided by the product of the charge and the distance between the charges separated.

Each molecule has dipole moments : Each molecule has at least one bond.Each bond gives rise to the dipole moment and the dipole moment of a molecule is decided by the addition of all the dipole moments arising from all the bond vectorially.

How are the dipole moments in a bond created:The dipole moments arises due to the electro negativity differnce between the two atoms forming the bond.If there is a difference in electro negativity,the shared electron density (or simply electron) is shifted towards the more electro negative atom,hence the more electro negative atom becomes overall partially positive and the other partially negative.This causes the separation of charge between the two atoms due to the bond.Hence each bond can give rise to the dipole moment. Such bonds which gives rise to the non zero dipole moment is called as the dipole moment.Remember,that the bonds between two similar atoms do not give rise to the non zero dipole moment. For example,H2 is a non polar molecule due to zero dipole moment.

Net dipole moment and polarity of a molecule: The dipole moment is calculated by the vector addition of all the dipole moments which arise from the polar bond. If the net dipole moment is non zero,then the molecule is called as polar ,otherwise it is non polar.

Polar molecule and polar bond are different concepts: A polar molecule and a polar bonds are two different concepts. If a molecule has any polar bond,it does not ensure the polarity of a molecule is the net dipole moment not the presence of the dipole moments which decides it.For example,CO2,has two C-O and each bond has a dipole moment,due to the difference in the electro negativity difference between C and O.Bht these two dipole moments are aligned 180 degree to each other and hence they cancel each other .so the net dipole moment is zero and hence the molecule is non polar.