Which of these has the strongest force of attraction between its molecules
Strongest: Hydrogen bonding. This occurs when compounds contain O−H, N−H, or F−H bonds. Though referred to as "hydrogen bonding", it's not a real bond but just a really strong intermolecular force.
Less strong: Dipole-dipole forces. This takes place when polar compounds are attracted to one another.
Weakest: London Dispersion Forces. This takes place when temporary dipoles on nonpolar molecules attract one another.
Note that intramolecular forces like covalent and ionic bonding are still much stronger than any form of intermolecular bonding.