Question

Please tell me, why is b-f bond in bf3 highlt polar but the bf3 molecule is non polar?

Answer 1

Molecular Polarity

When there are no polar bonds in a molecule, there is no permanent charge difference between one part of the molecule and another, and the molecule is nonpolar
A molecule can possess polar bonds and still be nonpolar. If the polar bonds are evenly (or symmetrically) distributed, the bond dipoles cancel and do not create a molecular dipole.the three bonds in a molecule of BF3 are significantly polar, but they are symmetrically arranged around the central boron atom. No side of the molecule has more negative or positive charge than another side, and so the molecule is nonpolar

and what i am saying is according to Lewis structure