A compound's empirical formula is N2O5. If the formula mass is 108 amu, what is the molecular formula?

What does that mean you dum bum

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   

Use a magnet to separate iron, evaporate water, i'm not sure how to separate the other two i'm sorry but good luck

The answer is c - the principal of original lateral continuity.