Which of the following compounds possesses zero dipole moment?

Solution:

• Carbon tetrachloride molecule has zero dipole moment even though C and Cl have different electronegativities and each of the C - Cl bond is polar and has some dipole moment. 
• This is because, the individual dipole moments cancel out because of the symmetrical tetrahedral shape of the molecule.
• In benzenes molecule carbon and hydrogen have distinct electronegativities, so it has the symmetrical planar structure. 
• It has six C-H bonds or six dipole moments, that cancel out another one, and therefore the net dipole moment is zero.
• The zero dipole moment of BF₃ is because of its symmetrical (triangular planar) structure. 
• The three fluorine atoms lie at the corners of an equilateral triangle with a boron at the center. 
• BF₃ molecule is formed by bonding between three sp² orbitals of B and p orbital of 3 F atoms.