Under the same conditions of temperature and pressure, which of the following gases would behave most like an ideal gas? A)He(g) B) NH3(g) C) Cl2(g) D) CO2(g)

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