Chemical Bonding and Molecular Structure

CH4,BF3,CO2 all has zero dipole moments.
Dipole moments is given by µ=√n(n+2) B.M. where, n is the number of unpaired electrons on central atom, in CH4,C has 0 unpaired electrons,
Thus µ=√0(0+2)=0
Same is true for BF3 and CO2.