The reaction $R-C \equiv C-R \xrightarrow{H_2 / \text{Lindlar's catalyst}}$ gives the major product as ..............

Compound $(X)$ [styrene] is subjected to the following sequence of reactions: $(i)$ $Br_2/CHCl_3$, $(ii)$ $NaNH_2$ (excess), $(iii)$ $CH_3I$, $(iv)$ $H_2, Na/NH_3(l)$, giving Major Product $(Y)$. The molar mass of the major product $(Y)$ formed is . . . . . . $\text{g mol}^{-1}$. (Given molar mass in $\text{g mol}^{-1}$: $C:12, H:1$)

The general formula for an acyclic alkyne is.....

Predict the nature of $P$ in the following reaction:
$CH_3-C\equiv C-CH_3 \xrightarrow[heat]{NaNH_2 / \text{inert solvent}} P$

Which of the following gases,when passed through a warm dilute solution of $H_2SO_4$ in the presence of $HgSO_4$,gives acetaldehyde?

$C_6H_5-C \equiv C-CH_3 \xrightarrow[H_2SO_4]{HgSO_4, H_2O} A$. The major product $(A)$ is: