Metal Oxides have an oxidation variety of -2 and customarily comprise an oxygen anion. The Earth’s crust is generally made up of oxides which can be stable.????? ?? ?? ???? ?????? – ???? ?? ??? ???? ???? ???????? ??? ???? ? ??? ???? ?? ????? ??? ??? ???? ??? ????? ??? ????? ??? ???? ? ?????? ???????? ??? ??? ?????? ??? ???? ??? ?????? ??? ???.?