The intermolecular forces that best describe the solubility of CF₃CF₃ (hexafluoroethane) in liquid CO₂ are London dispersion forces.

Here's why:

* Both CF₃CF₃ and CO₂ are nonpolar molecules. This means they have no permanent dipoles and their primary intermolecular interactions are London dispersion forces.

* London dispersion forces arise from temporary fluctuations in electron distribution around a molecule, creating temporary dipoles. These temporary dipoles can then induce dipoles in neighboring molecules, leading to weak attractions.

* The strength of London dispersion forces depends on the size and shape of the molecule. Larger, more polarizable molecules have stronger London dispersion forces.

* Both CF₃CF₃ and CO₂ are relatively small molecules, but they are both highly polarizable due to the presence of fluorine atoms. This means they can experience relatively strong London dispersion forces with each other, allowing them to dissolve in each other.

Other factors to consider:

* Pressure: The solubility of gases in liquids generally increases with pressure. Supercritical CO₂, which is CO₂ at a high pressure and temperature, is a common solvent for nonpolar compounds.

* Temperature: Solubility generally decreases with increasing temperature. However, there are exceptions, especially when dealing with supercritical fluids.

In summary: While other intermolecular forces may play a minor role, the primary force responsible for the solubility of CF₃CF₃ in liquid CO₂ is London dispersion forces.