Which of the following is/are amphoteric?

Amphoteric substances can act as both acids and bases. Aluminium hydroxide, Al(OH)3, is a well-documented amphoteric hydroxide that reacts with both acids and bases to form salts [1]. While many metal oxides and hydroxides are purely basic, Al(OH)3 and ZnO are notable exceptions [1]. The bicarbonate ion (HCO3-) is also amphoteric (specifically amphiprotic) because it can donate a proton to become a carbonate ion (CO3^2-) or accept a proton to become carbonic acid (H2CO3). In contrast, Fe(OH)3 is generally considered a basic hydroxide and is not typically classified as amphoteric in standard chemical contexts. Similarly, NaOH and Ba(OH)2 are strong bases and do not exhibit acidic behavior. Therefore, the pair containing Al(OH)3 and HCO3- correctly identifies two amphoteric species.

Sources

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