When acetaldehyde is heated with Fehling solution,a red precipitate is formed. Which of the following is that?

Which of the following arrangements with respect to their reactivity in nucleophilic addition reaction is correct?

Identify $P$ and $Q$ respectively of the following reaction.

Which of the following gives Fehling's solution test?

Treatment of propionaldehyde with dilute $NaOH$ solution gives:

$A$ molecule $(X)$ with the following structure is hydrolyzed under mild acidic conditions to produce $(Y)$ and $(Z)$. Identify the correct statements about $(Y)$ and $(Z)$.