Which one of the following oxides dissolves in water ?
CuO
Al<sub>2</sub>O<sub>3</sub>
Fe<sub>2</sub>O<sub>3</sub>
Na<sub>2</sub>O
Answer is Right!
Answer is Wrong!
This question was previously asked in
UPSC NDA-1 – 2016
– Al₂O₃ is aluminium oxide, an amphoteric oxide (reacts with both acids and bases), and is generally insoluble in water.
– Fe₂O₃ is iron(III) oxide, an iron oxide, which is insoluble in water. It is a basic oxide.
– Na₂O is sodium oxide, an alkali metal oxide. It reacts vigorously with water to form sodium hydroxide (NaOH), a soluble base: Na₂O(s) + H₂O(l) → 2NaOH(aq). Thus, Na₂O effectively dissolves by reacting with water.