Which one of the following pairs has only London dispersion forces as the intermolecular force between them?

Question

1.) H2O; HF
2.)He; He
3.) HCl; HCl
4.) Ne; HCl

please help I am so lost

Answer 1

London dispersion forces are present is essentially all molecules but they are only one of several intermolecular forces. Ion-dipole, dipole-dipole, hydrogen bonding, etc are others but they always occur because of some polarity between molecules. For example, both H2O and HF are polar molecules. So the secret to answering this question is to pick out the pair where there is no polarity associated with any molecule of the pair.
Which do you think that is?.

Answer 2

He; He?

Answer 3

Yes, very good.

Answer 4

Good question

Answer 5

nub