The major product formed in the reaction is

The product $(C)$ in the following sequence of reactions has . . . . . . . . $\pi$ bonds.

Which of the following compounds is the most acidic?

$A$ compound $(A)$ has the molecular formula $C_2H_4O_2$ and it gives the following reactions:
$(i)$ Addition of the above compound to a sodium carbonate solution gives effervescence of $CO_2$ gas and forms compound $(P)$.
$(ii)$ When compound $(P)$ is heated with sodalime,it gives gas $(Q)$. Identify $(A)$,$(P)$,and $(Q)$ and provide the reactions.

$CH_3CO_2C_2H_5$ on reaction with sodium ethoxide in ethanol gives $A$,which on heating in the presence of acid gives $B$. Compound $B$ is

The strongest acid among the following is