The four bonds of carbon tetrachloride (CCl4<span>) are </span>polar, but the molecule isnonpolar<span> 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 </span>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.
