Consider the following sequence of reactions.
$C_6H_5COONa$ $\xrightarrow[\Delta]{NaOH/CaO} X$ $\xrightarrow[\text{Anhy. } AlCl_3]{CO/HCl} Y$ $\xrightarrow[NaOH]{\text{conc. }} A + B$.
If $A$ is the reduction product of $Y$,what is $B$?

Given below are two statements $:$
Statement $(I) :$ Vanillin, which has a benzene ring substituted with a methoxy group, a hydroxyl group, and an aldehyde group, will react with $NaOH$ and also with Tollen's reagent.
Statement $(II) :$ Vanillin will undergo self-aldol condensation very easily.
In the light of the above statements, choose the most appropriate answer from the options given below $:$

Given below are two statements,one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: $3$-chloro-$2$-methylpentan-$3$-one can be subjected to Wolff-Kishner reduction to give $3$-chloro-$2$-methylpentane.
Reason $R$: Wolff-Kishner reduction is used to convert $C=O$ into $CH_2$.

What is the percentage of formaldehyde in formalin (in $\%$)?

The general name of the compound formed by the reaction between aldehyde and alcohol is

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