When Priestly put a mouse in his new air, he was to see it lived as a mouse lives in normal air.

The answer would be

The mass has escaped into a gas which you can not see so the law stays true.

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   

Answer(true);