A crystalline substance of green colour 'X' emits gases of characteristic odour when heated over a flame. It first loses water and changes colour. On further heating, it decomposes and produces a solid compound Y.

(a) Identify 'X' and 'Y'.

(b) State the change in colour observed when 'X' is heated.

The question describes a crystalline substance 'X' that emits gases of characteristic odour when heated over a flame. It first loses water and changes colour. On further heating, it decomposes and produces a solid compound Y. Based on the description, 'X' is copper sulphate and 'Y' is anhydrous copper sulphate. The colour changes from blue to white.