Question

Which of the following is the most basic oxide?
(A) $S{{b}_{2}}{{O}_{3}}$
(B) $B{{i}_{2}}{{O}_{3}}$
(C) $Se{{O}_{2}}$
(D) $A{{l}_{2}}{{O}_{3}}$

Answer 1

Hint: The basicity of an oxide depends on the size of the central atom, the oxidation number of the central atom and the metallic character of the element. Larger the size, more metallic is the oxides which in turn increases the basicity.

Complete step by step solution:
Let’s look at the answer to the given question:
> We all know that there are three types of oxides:
1) Acidic oxides: These oxides are acidic in nature. They react with bases. They are usually formed by non-metals.
2) Basic oxides: These oxides are basic in nature. They react with bases. They are usually formed by metals.
3) Amphoteric oxides: These oxides are both acidic and basic in nature. They give reactions with both acids and bases.
Now, we will analyze the given options and find out the answer.
- In option (A) $S{{b}_{2}}{{O}_{3}}$ is given. Sb belongs to the 15 group. It is a metalloid. It shows both metallic as well as non-metallic character. So, the oxide formed by this metal is amphoteric in nature.
- In option (D) $A{{l}_{2}}{{O}_{3}}$is given. Al belongs to group 13. It forms an amphoteric oxide. This is because of the relatively small size of Al atom.
- In option (C) $Se{{O}_{2}}$ is given. She belongs to the group 16. It is non-metal and forms an acidic oxide.
- In option (B) $B{{i}_{2}}{{O}_{3}}$is given. Bi belongs to the 15 group. It forms a basic oxide. This is because as we go down the group the metallic character increases. So, Bi has increased metallic character. Hence, it forms a basic oxide.
So, we have seen that out of the given oxides, $B{{i}_{2}}{{O}_{3}}$ is the most basic oxide.
Hence, the answer of the given question is option (B).

Note: The basicity of an oxide generally depends on the electropositive nature of the central atom. Electropositive means the ability to release electrons to form cations. This is why most basic oxides are metallic oxides.