Answer:
So, X is magnesium oxide and Y is magnesium hydroxide.
Explanation:
When magnesium is burnt in air, it reacts with oxygen to form a powdery ash known as magnesium oxide (X). The chemical reaction can be represented as follows:
2Mg (s) + O2 (g) -> 2MgO (s)
When magnesium oxide (X) is dissolved in water, it reacts to form magnesium hydroxide (Y). The chemical reaction can be represented as follows:
MgO (s) + H2O (l) -> Mg(OH)2 (aq)
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