Th ordu polasut nha 3 0nd &fa a b 8f3 < nf3 nhg bf nha (c

Bf3 is non polar zero dipole moment

and dipole.moment of Nh3 is greater than Nf3

so order Bf3

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BF3 has sp2 hybridization and no lone pairs so mu =0

in case of NH3 and NF3, the the direction of dipolemoment of H in NH3 is towards lone pair dipole moment so it gets max dipole moment

In NF3, EN of F is more than H so it pulls electron density towards it self so direction of dipolemoment is reversed to dipole moment of lone pair so overall dipole moment decreased as compared to NH3

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Dipole moment of NH3 is higher than NF3 molecule. Both the molecules have pyramidal shape with a lone pair of electrons on nitrogen atom. There is a greater difference in electronegativity between nitrogen and hydrogen thanthere is between nitrogen and fluorine

BF3 is a non polar compound

See this

As shown in the figure above, the dipole moments due to 3 N-H bonds and that due to the lone pair are in the same direction and add up to give a net dipole moment to NH3 molecule whereas in NF3 molecule, the resultant dipole moment due to 3 N-F bonds opposes the dipole moment due to the lone pair. These opposing dipoles when added give a net dipole moment to NF3 molecule which is the difference of these two opposing dipole moments, which in turn leads to a small value of dipole moment to NF3 molecule making it less polar than NH3.