Question

Nh3 and nf3 have dipole moment which are opposite direction in chemistry

Answer 1

 In NF3, F is more electronegative than N. So, all F atoms pull the electrons towards themselves. And, this resultant moment isopposite to the directions of that of the lone pair of electrons on the 'N' atom. ... And, so we have NH3 whose dipole moment is much higher than that of NF3.