Answer:
Only BF₃ is non polar.
Explanation:
The non polar molecule is one which will have zero dipole moment.
This zero dipole moment is possble if
a) the bonds are non polar (completely) and there is no lone electrons
b) the bonds are polar but the overall dipole moment cancel each other due to planar geometry of molecule
i) BF₃ : This is trigonal planar molecule. The overall dipole moment is zero due to symmetric distribution of electrons and thus dipole cancel each other.
ii) NF₃ : there is lone pair of electron and the bonds are polar.
iii) PBr₃: Again presence of lone pair of electrons and thus ssymmetric distribution of electrons
iv) BrCl₃ : The bonds are polar and molecule is not planar.
v) IF₃ : bonds are polar.
