The simplified model of the hall effect proved that the current (electric) in metals are carried by electrons and not protons. The hall effect introduced the hall coefficient which is the ratio of the induced electric field to the current density x applied magnetic field. This coefficient is unique for each type of metal.
The combining of hydrogen and oxygen gas into liquid=H2O (water) is a compound or a molecule because it is 2 different elements combined with chemical bonds so its Chemical. B
