Which of the following does $NOT$ give a yellow precipitate when reacted with a $(NaOH + I_{2})$ mixture?

$A$ carbonyl compound $X$ $(C_8H_8O)$ undergoes disproportionation with conc. $KOH$ on heating. The product of $X$ with $Zn-Hg/HCl$ is $Y$ and the product of $X$ with $NaBH_4$ is $Z$. What are $Y$ and $Z$ respectively?

Arrange the following compounds in their decreasing order of reactivity towards nucleophilic addition reaction: $CH_3COCH_3$,$CH_3COC_2H_5$,$CH_3CHO$.

Which of the following compounds will not react with phenylhydrazine?

Which of the following is not the product of an intramolecular aldol condensation?

$Propyne$ $\xrightarrow[Hg^{2+} / H_2 O, \Delta]{H^{+}}$ $P$ $\stackrel{Ba(OH)_2}{\rightleftharpoons}$ $Q$ $\xrightarrow{\Delta}$ $R$. $R$ in the above sequence of reactions is: