What is the distance from the nucleus to the outer most electrons?

Atomic radius is the distance from the atom's nucleus to the outer edge of the electron cloud.

True, the standard unit for volume is liters which can be represented by either a lower case "l" or a capital "l"

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