Which among the following metals provides amphoteric oxide?
(1) Sodium
(2) Silver
(3) Aluminium
(4) Calcium
Answer: (3) In chemistry, an amphoteric species is a molecule or ion that can react as an acid as well as a base. Many metals (such as zinc, tin, lead, aluminum, and beryllium) and most metalloids form amphoteric oxides or hydroxides. Amphoterism depends on the oxidation state of the oxide. One type of amphoteric species is amphiprotic molecules, which can either donate or accept a proton (H+). Examples include amino acids and proteins, which have amine and carboxylic acid groups, and self-ionizable compounds such as water and ammonia.
