What is the average atomic mass of silicon given the following abundance information on the isotopes of silicon? [Si-28 (mass 28 amu) has an abundance of 92.21%]
[Si-29 (mass 29 amu) has an abundance of 4.70%]
[Si-30 (mass 30 amu) has an abundance of 3.09%]

C. chemical changeshope i : )

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