Concept: is the chemical formula for aluminium oxide, an inorganic chemical reagent. Alpha-alumina, alumina, alundum, and aloxide are some of their alternate names. Aluminium oxide may react with both acids and bases. These substances are known as amphoteric compounds because they have the ability to react with both acids and bases. . This metal oxide can act as acid or base depending on the reaction conditions. For example, consider the reaction of with strong base Here acts as an acid and forms a conjugate base which further forms a salt. Now the reaction of with strong acid is as follows; Hence, is an amphoteric oxide. Hence, the correct answer is option 3.