Which property is not important when selecting a material to use as a light bulb filament?

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   

Mg-26 and mg-24 are pair of isotopes. isotopes are defined as atoms of the same element having same atomic number but different mass number. i hope that was .