What will be the product of the following reaction?

Which of the following compounds will not undergo tautomerism?

In the following reaction,
$CH_3-C \equiv CH$ $\xrightarrow[H_3O^+]{Hg^{2+}} X$ $\xrightarrow[PhCHO]{dil. NaOH} Y$
$X$ and $Y$,respectively,are

The reaction $R-C(=O)-R + HCN \xrightarrow{\text{catalyst}} R-C(OH)(CN)-R$ is a nucleophilic addition reaction. Which of the following can be used as a catalyst in the above reaction?

Which of the following aldehydes is most reactive towards nucleophilic addition reactions?

Benzene on reaction with acetyl chloride in the presence of anhydrous $AlCl_3$ gave the product $P$. The product $P$ on reaction with methyl magnesium bromide followed by treatment with water furnished the product $Q$. The molecular formula of $Q$ is