which of the mccachansims is currently operating & which of the mccachansims will become more important??

Copper, silver, aluminum, cobalt, chromium, mercury 

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