Which combination will make a buffer? naoh and nacl koh and kcl hcl and nacl ch3cooh and ch3coona

and

Exothermic,  physical change after it is already baked

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