We need to know different types of van der Waal's forces.
There are three different van der Waal's forces.
van der Waal's force is driven by induced electrical interactions between two or more atoms or molecules. Though it is very weal in nature, this force is ultimately responsible for liquefaction and solidification of gases.
van der Waal's forces are non-directional. The strength of this force increases as the size of the units linked increases.
There are three types of van der Waal's interactions. They are- (i) Ion-dipole interaction, (ii) dipole-dipole interaction and (iii) hydrogen bond.
Ion dipole interaction is weakest among these three, dipole-dipole interactions are medium and hydrogen bonds are strong interactions.