Qualities of a mineral that classify it as ore

Usefulness and profitability are the qualities of a mineral that classify it as an "ore".

This means that when the Geologist's who studied minerals, they classified them. It's standards in classification is meant to show elements and metals that are can profitably extracted from a rock.  

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.

the electrical  conductivity  of asolution  of an electrolyte is measured by determining the resistance of thesolution  between two flat or cylindrical electrodes separated by a fixed distance.