To distinguish between two carbonyl compounds, typically aldehydes and ketones, specific reagents are used. Here, we need to identify which reagent can distinguish "P" and "Q" produced from the hydrolysis of an unsaturated ether.
Based on the explanation above, Fehling solution is the correct answer. It distinguishes "P" and "Q" because Fehling's solution reacts with aldehydes to form a red precipitate, while most ketones do not undergo this reaction.
Observe the following reaction and same reaction is carried out with the following compound: 
X and Y can be differentiated by:
A student is given one compound among the following compounds that gives positive test with Tollen's reagent. The compound is: 