Pf3 has a dipole moment of 1.03 d butbf3
has a dipole moment of zero. explain thedifference.

The difference between both molecules can be explained on the basis of valance shell electron pair repulsion theory (VSEPR).  

Explanation:

The difference between both molecules can be explained on the basis of valance shell electron pair repulsion theory (VSEPR).  

PF3 which is lone pair reside on phosphorus has a tetrahedral structure and it is trigonal pyramidal. As all fluorine of molecules present on the same side, therefore, dipole doesn't cancel out hence have some dipole moment while on the other side, BF3 which is trigonal planar molecules, thus bond polarities of molecules are canceled thus giving zero net dipole moment.