Dipole moment is a measure of the net polarity of a molecule, resulting from the vector sum of individual bond dipoles and contributions from lone pairs. - BF₃: Boron trifluoride has a central Boron atom bonded to three Fluorine atoms. Boron is sp² hybridized, and the molecule is trigonal planar. The B-F bonds are polar, but the three bond dipoles are symmetrically arranged at 120° to each other in a plane. Their vector sum is zero, so BF₃ has a zero net dipole moment. - NF₃: Nitrogen trifluoride has a central Nitrogen atom bonded to three Fluorine atoms and one lone pair. Nitrogen is sp³ hybridized, and the molecule is trigonal pyramidal. N-F bonds are polar (F is more electronegative). The bond dipoles point towards the F atoms, away from N. The lone pair contributes a dipole moment pointing away from N. The N-F bond dipoles and the lone pair dipole are in opposite directions along the molecular axis, partially canceling each other. This results in a small net dipole moment for NF₃. - NH₃: Ammonia has a central Nitrogen atom bonded to three Hydrogen atoms and one lone pair. Nitrogen is sp³ hybridized, and the molecule is trigonal pyramidal. N-H bonds are polar (N is more electronegative). The bond dipoles point towards the N atom. The lone pair contributes a dipole moment pointing away from N. Both the N-H bond dipoles and the lone pair dipole point in the same general direction (upwards along the molecular axis), reinforcing each other. This results in a significant net dipole moment for NH₃. Comparing NF₃ and NH₃, the dipole moment of NH₃ is significantly larger than that of NF₃. Therefore, the order of increasing dipole moment is BF₃ (0)