Balance the following equation (a.) CaC2 + 2H2O → Ca(OH)2 + C2H2
(b.) (NH4)2 Cr2O7 → Cr2O3 + N2 + 4H2O
(c.) 2CH3NH2 + 9O2 → 2CO2 + N2 + 5H20

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   

Answer two atoms of oxygen;