Section: Chemistry: Section I

14) In which of the following does hydrogen have an oxidation number of -1?

1. H₂O
2. H₂
3. NaH
4. NaOH

Usually hydrogen has an oxidation number of +1. However, with the active metals of Group 1 it is possible for hydrogen to have an oxidation number of -1. This occurs because these metals so readily lose electrons that H atoms are forced to accept them thereby becoming H^-1.