Question

Carbon tetrachloride, CCL4, is nonpolar.

What force holds the molecules together?

Answer 1

Covalent bonds between C and Cl (note it isn't a capital L but Cl). Although the molecule as a whole is non-polar, each C-Cl bond is slightly polar because the electronegativity of C is 2.5 and that of Cl is 3.0. The bonding, however, is largely shared electrons with a covalent bond.