Question

Which of the following are amphoteric oxides? (This question has multiple correct answers)
(a)- $Sn{{O}_{2}}$
(b)- $A{{l}_{2}}{{O}_{3}}$
(c)- $G{{a}_{2}}{{O}_{3}}$
(d)- $Si{{O}_{2}}$

Answer 1

The amphoteric oxides are those oxides that mean it can act as both acidic and basic, i.e., with acid it acts as a base, and with the base, it acts as an acid. As we move down the group the acidity of the oxides and hydroxides of the p-block elements decreases.

Complete step by step answer:
The oxide of the element means the element is combined with an oxygen atom. The oxides of p-block elements can act like acid, base, and amphoteric compounds. The amphoteric oxides are those oxides that mean it can act as both acidic and basic, i.e., with acid it acts as a base and with the base, it acts as an acid. As we move down the group the acidity of the oxides and hydroxides of the p-block elements decreases. So the oxides of group 13 have formula ${{B}_{2}}{{O}_{3}},\text{ }A{{l}_{2}}{{O}_{3}},\text{ }G{{a}_{2}}{{O}_{3}},\text{ }I{{n}_{2}}{{O}_{3}},\text{ }and\text{ }T{{i}_{2}}O$ whose names are boron oxide, aluminium oxide, gallium oxide, indium oxide, and thallium oxide. So as we move down the acidic nature of oxides decreases. Therefore, boron oxide is acidic, aluminium oxide and gallium oxide are amphoteric, and indium oxide and thallium oxide are basic. So the oxides of group 14 have formula $C{{O}_{2}},\text{ }Si{{O}_{2}},\text{ Ge}{{O}_{2}},\text{ Sn}{{O}_{2}},\text{ }and\text{ Pb}{{O}_{2}}$ whose names are carbon dioxide, silicon dioxide, germanium dioxide, tin dioxide, and lead dioxide. So carbon dioxide, silicon dioxide, and germanium dioxide are acidic but tin dioxide and lead oxide are amphoteric.

Therefore, the correct answers are an option (a), (b), and (c).

Note: As the nature of oxides of group 13 decreases down the group, then the same trend is for the hydroxides of group 13. Since the basic nature of oxides increases down the group 14 due to which the oxidizing property of the oxides increases.