What kind of oxide are each of the following? Choode from following: Acidic, basic, amphoteric, molecular, molecular acidic, molecular basic, molecular amphoteric. 2.) Rb 2 O 3.)Â Â Al 2 O 3 Solution 1) As2O5 dissolves in water to give an oxyacid As2O5 + 3H2O --> 2H3AsO4(aq) So, As2O5 is acidic 2) Rb2O dissolves in water to give RbOH, a base Rb2O + H2O -----> 2RbOH So, Rb2O is basic 3) Aluminium oxide is an amphoteric substance, meaning it can react with both acids and bases, such as hydrofluoric acid and sodium hydroxide, acting as an acid with a base and a base with an acid, neutralising the other and producing a salt. Al 2 O 3 + 6HF ------2 AlF 3 + 3 H 2 O Al 2 O 3 + 2NaOH + 3 H 2 O -----> 2 NaAl(OH) 4 (sodium aluminate) So, Al2O3 is amphoteric in nature .