The reduction product of ethyl $3$-oxobutanoate by $NaBH_4$ in methanol is

Two aliphatic aldehydes $P$ and $Q$ react in the presence of aqueous $K_2CO_3$ to give compound $R$,which upon treatment with $HCN$ provides compound $S$. On acidification and heating,$S$ gives the product shown below:
$1.$ The compounds $P$ and $Q$ respectively are:
$2.$ The compound $R$ is:
$3.$ The compound $S$ is:
Give the answer for questions $1$,$2$ and $3$.

Identify $P$ and $Q$ respectively of the following reaction.

Which of the following reactions gives a carboxylate ion in their reaction mixture?

The product $(D)$ will be

Which of the following compounds would not give tert-butyl alcohol when treated with excess methylmagnesium bromide $(CH_3MgBr)$ followed by acid?