Identify the symmetrical ketone from the following compounds.

The compound $(X)$ in the given reaction is:

How will you convert ethanal into the following compounds?
$(i)$ Butane$-1,3-$diol
$(ii)$ But$-2-$enal
$(iii)$ But$-2-$enoic acid

What products are formed on the reaction of $Propanal$ with $2-Methylpropanal$ in the presence of $NaOH$? Write the name of the reaction.

Identify the product of the following reaction:
$CH_3-CO-CH_2-CH_2-CH_2-CHO \xrightarrow{NaOH, \Delta} \text{Product}$

$p$-cresol reacts with chloroform in an alkaline medium to give compound $A$,which adds hydrogen cyanide to form compound $B$. The latter,on acidic hydrolysis,gives a chiral carboxylic acid. The structure of the carboxylic acid is: