When acetaldehyde is reacted with $LiAlH_4$,what is the product formed?

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

Identify the product in the following reaction :
$3$-acetylbenzaldehyde $\xrightarrow{Zn-Hg, HCl}$ Product

Which reaction is correctly matched with its name?

What will be the major product?

$Ph-CO-CH_3 \xrightarrow[H_2O]{Mg-Hg}$ Product. The main product is: