How many of the following molecules contain polar covalent bonds but net dipole…

CHEMISTRY · Subjective · A Level · Chemistry · Bonding · Bonding

Problem

How many of the following molecules contain polar covalent bonds but net dipole moment is almost zero

BF_3, CCl_4, SiCl_4, CO_2, SO_3, NO_3^-, CO_3^{2-}