[Abder-Rahman]

I just want to ask about the intermolecular forces that exist between the HCl molecules. I know that it is clear that it is a permanent dipole-permanent dipole interactions. But, on a worksheet that I have, it also mentions that "London Dispersion Interactions" exist. How is that?

[JustinCh3m]

LDF forces (van der Waal's forces) exist in all molecules (or atoms) that contain electrons.  They're usually associated with "nonpolar" entities because they're the ONLY IMF's in nonpolar molecules (or atoms)

Look up "instantaneous dipoles" in your text for more info...