19 which term represents an intermolecular force in a sample of water

Because there no choices there, most probably it should be about hydrogen bonding in the water, which is the most important intermolecular force in water.

Ch4 and ph3 are both covalent since they are composed both of non-metals.    ch4 is non- polar because of  london forces and has a geometry of tetrahedral  ph3 , on the other hand, is umbrella shaped polar and has dipole-dipole intermolecular force (imf) . since ph3 is polar, it has a stronger imf