Which one of the following oxides is most basic?

CONCEPT:

Basicity of Oxides

• The basicity of oxides depends on the electronegativity of the element and the nature of the oxide.
• Oxides of metals generally tend to be basic, whereas oxides of non-metals tend to be acidic.
• The basic nature of an oxide increases as we move down a group in the periodic table, because the metallic character increases.
• The basicity of an oxide also increases as the oxidation state of the metal decreases. Lower oxidation states tend to form more basic oxides.

EXPLANATION:

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  • Sb₂O₃ (Antimony(III) oxide): Antimony is a post-transition metal, and the oxide is moderately basic.
  • Bi₂O₃ (Bismuth(III) oxide): Bismuth is a heavier post-transition metal, and its oxide is also basic but less so compared to Sb₂O₃.
  • SeO₂ (Selenium dioxide): Selenium is a non-metal, and its oxide is acidic in nature.
  • Al₂O₃ (Aluminum oxide): Aluminum is a metal, and its oxide is amphoteric, meaning it can act both as an acid and as a base depending on the conditions.
• Among the given oxides, Bi₂O₃ is most basic, as it is from a metal with a lower oxidation state and is less acidic or amphoteric compared to the others.

Therefore, Bi₂O₃ is the most basic oxide among the given options.