Since the process of a chemical change and a chemical reaction both result in a new substance being formed, we know that: Your

A. The Law of Conservation of Matter does not apply to them.
B. A physical change is also the same thing as a chemical reaction.
C. A chemical change and a chemical reaction are the same thing.

Copper, silver, aluminum, cobalt, chromium, mercury 

You would be correct, boiling water does disinfect contamination.    the property of disinfecting means to kill  germs, bacteria and other pathogens or contamination  that might cause an infection or cause a person to become sickly. a couple methods of disinfecting are using soap, other cleaning supplies or by simply "boiling" the contaminate.  the reason why boiling water disinfects certain attributes is because some cells cannot survive the heat and pressure.

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   

Ametal with a large number of free flowing electrons most likely has good conductivity