the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.
As a part of an experiment a student burns propane to produce carbon dioxide and water she remembers that she must follow the law conservation of matter when writing a balanced chemical equation which of these equation adheres to the law of conservation of matter