Name two metals that do not always lose the same number of electrons when they form ionic bonds. How can you tell?

plss help TwT

1 answer

Cu is +1 and +2. Forms two compounds with chlorine; i.e., CuCl and CuCl2 or CuO and Cu2O.
Hg is +2 and +2. HgCl and Hg2Cl2.
PbO and PbO2
FeO and Fe2O3
etc