JEE Main 2023 · 6 April · evening · Single correct · +4 / −1
Group-13 elements react with O₂ in amorphous form to form oxides of type M₂ O₃ (M= element). Which among the following is the most basic oxide?
- (a) Al₂O₃
- (b) TI₂O₃
- (c) B₂O₃
- (d) Ga₂O₃
Answer and solution
Answer (b) TI₂O₃
Solution
Chemistry ma’am · 3 steps
Go down the boron family and the metal character rises, so the oxide at the bottom is the most basic.
- Trend down the group. From B to Tl, atomic size increases and ionisation enthalpy falls overall. The element becomes more metallic, and metallic oxides are basic.
Oxide Element character Nature of oxide B₂O₃ non-metal acidic Al₂O₃ metal amphoteric Ga₂O₃ metal amphoteric Tl₂O₃ most metallic basic - Why Tl wins. Tl is the heaviest element in this list. Its oxide reacts with acids and does not dissolve in alkalis, so it shows the strongest basic character.
- So. The most basic oxide is Tl₂O₃, option (b).
The idea to keep. Within a group, oxides go from acidic to amphoteric to basic as you move down. For group 13: B acidic, Al and Ga amphoteric, In and Tl basic.
Answer from the NTA final answer key. Solution by PrepWiser.