As ions are charged species a strong interactions(attractions) are possible between the oppositely charged ions. Where as london dispersion forces(vanderwaal forces) are weak forces as they are induced dipole-dipole attractions, these are temporary and weak attractions. ex: between Na+& Cl- strong ionic attractions are present. between 2 molecules of water london forces involve. and hence NaCl has high mp & bp than H2O Solution As ions are charged species a strong interactions(attractions) are possible between the oppositely charged ions. Where as london dispersion forces(vanderwaal forces) are weak forces as they are induced dipole-dipole attractions, these are temporary and weak attractions. ex: between Na+& Cl- strong ionic attractions are present. between 2 molecules of water london forces involve. and hence NaCl has high mp & bp than H2O.