The ranking from strongest to weakest London dispersion forces is: CCl₄ > CO > BaS
London dispersion forces, sometimes referred to as dispersion forces or van der Waals forces, are a kind of intermolecular force that are produced when there are brief variations in the distribution of electrons, which cause transient dipoles to form.
In general, the size and shape of molecules increase the strength of London dispersion forces.
BaS is an ionic compound with a metal cation (Ba²⁺) and a non-metal anion (S²⁻). London dispersion forces are generally weaker in ionic compounds compared to covalent molecules.