Which one of the following oxides reacts with both acid and base?

Metal oxides are generally basic in nature, while non-metal oxides are typically acidic [2]. However, certain metal oxides exhibit both acidic and basic behavior; these are classified as amphoteric oxides [1]. Aluminium oxide (Al2O3) is a primary example of an amphoteric oxide [1]. It reacts with acids, such as hydrochloric acid, to form aluminium chloride and water, demonstrating its basic nature. Simultaneously, it reacts with strong bases like sodium hydroxide to form sodium aluminate and water, demonstrating its acidic nature. In contrast, sodium oxide (Na2O), calcium oxide (CaO), and potassium oxide (K2O) are strictly basic oxides [1]. These basic oxides react with water to form strong hydroxides and react with acids to form salts, but they do not react with bases [3]. Therefore, only aluminium oxide reacts with both acids and bases [1].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > Activity 3.9 > p. 41
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > Activity 3.8 > p. 40
3. [3] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > Activity 3.10 > p. 43