How many molecules among the following have zero dipole moment: NH3, BF3, NF3, CCI4?

i.  N¨H3⇒sp3 hybridised ⇒ pyramidal ⇒μ≠0 ii. BF3⇒sp2 hybridised ⇒ planar and symmetrical ⇒μ=0. iii. NF¨3⇒sp3 hybridised ⇒ pyramidal ⇒μ≠0.  iv. CCl4⇒sp3 hybridised ⇒  symmetrical ⇒μ=0Hence, BF3 and CCl4 have zero dipole moment.