How is CCl4 non polar?

Carbon tetrachloride is non-polar due to the symmetric tetrahedral shape of the molecule which cancels the polarity between Cl-C bond. When one Cl atom is changed by another atom then the molecule becomes polar. Hope this answers the question.

The four bonds of carbon tetrachloride (CCl4) are polar, but the molecule isnonpolar because the bond polarity is canceled by the symmetric tetrahedral shape. When other atoms substitute for some of the Cl atoms, the symmetry is broken and the molecule becomes polar