In general, ethers have a much lower boiling point than their isomeric alcohols. why? the carbon-oxygen bond in ethers is nonpolar. unlike alcohols, ethers cannot act as lewis bases. ethers are less reactive than alcohols. unlike alcohols, ethers cannot hydrogen bond with each other.

They can measure  the amount of energy gained or lost

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   

13 protons and 13 electrons