<Dd> H + CuO → Cu + H O </Dd> <P> Since metals that are reactive form oxides that are stable, some metal oxides must be electrolyzed to be reduced . This includes sodium oxide, potassium oxide, calcium oxide, magnesium oxide, and aluminium oxide . The oxides must be molten before immersing graphite electrodes in it: </P> <Dl> <Dd> 2Al O → 4Al + 3O </Dd> </Dl> <Dd> 2Al O → 4Al + 3O </Dd>

What type of oxide are formed when metal combine with oxygen