Let's analyze the reactions step by step to identify A, X, Y, and Z.
Reaction for A: The given compound X (C2H6O) is ethanol. When ethanol is oxidized using copper at 573 K, it forms acetaldehyde (ethanal). Therefore, A is ethanal.
Properties of A: Ethanal gives a silver mirror when reacted with Tollen's reagent, which confirms that A is an aldehyde.
Identification of Y: In the reaction sequence, A undergoes aldol condensation to form an α, β-unsaturated aldehyde. Therefore, Y is but-2-enal.
Identification of Z: When A (ethanal) reacts with hydrazine derivatives such as semicarbazide, it forms a semicarbazone. Hence, Z is semicarbazone.
Conclusion: Based on the above reasoning, the correct identification of compounds is: A - Ethanal, X - Ethanol, Y - But-2-enal, Z - Semicarbazone.
