B-Cl bond has a bond moment. Explain why `BCl_3` molecule has zero dipole moment.

Explanation

Dipolemoment of a molecule is vector sum of the dipole moments of all the bonds in the molecule . Although B-Cl bonds have bond moments , since the three bonds are oriented at an angle `120^@` to one another , the three bond moments give a net sum of zero as the resultant of any two is equal and opposite to the third.

So the dipole moment of `BF_3` is zero.