BF3 will have dipole moment as zero...if u study the hybiridised structure of NF3 u will see there is one lone pair..so the resultant bond momentum of three other bonds is decreased by the bond momentum of lone pair but dipole moment is not zero....but in case of BF3 there are no lone pairs...only three sigma bonds...so the resultand bond momentum of two sigma bonds(1,2) gets nullified by the bond momentum of the third sigma bond(3)...the resultant bond momentum of BF3 gets zero ...hence Dipole moment of BF3 is zero

BF3

- BF3 has a dipole moment of zero.
- This is because the molecule is symmetrical in shape.
- The three fluorine atoms are arranged symmetrically around the boron atom, creating a trigonal planar geometry.
- The dipole moments of the three B-F bonds cancel each other out due to the symmetric arrangement.
- As a result, the overall dipole moment of the BF3 molecule is zero.

NF3

- NF3, on the other hand, does not have a dipole moment of zero.
- This is because the molecule is not symmetrical.
- The lone pair of electrons on the nitrogen atom causes an uneven distribution of charge in the molecule.
- This results in a net dipole moment for NF3.
- The dipole moment of NF3 is towards the lone pair of electrons on the nitrogen atom, making it a polar molecule.