In the following reactions,what are $B$ and $X$ respectively?
$C_2H_5MgBr$ $\xrightarrow{ClCN} C_2H_5CN$ $\xrightarrow{H_3O^+} B$
$CH_3COCH_3$ $\xrightarrow[NaOH]{I_2} X + CHI_3$ $\xrightarrow{Ag} Y$
$C_6H_5NH_2$ $\xrightarrow[HCl]{NaNO_2} P$ $\xrightarrow{CuCN} Q$ $\xrightarrow{+4H} R$

The major product of the following reaction sequence is

The correct acidity order of the following compounds is:

The reaction of $CH_3CO_2C_2H_5$ with sodium ethoxide and ethanol gives product $X$. Heating $X$ in the presence of an acid gives $Y$. What is $Y$?

Give plausible explanation for each of the following:
$(i)$ Cyclohexanone forms cyanohydrin in good yield but $2,2,6-$trimethylcyclohexanone does not.
$(ii)$ There are two $-NH_2$ groups in semicarbazide. However,only one is involved in the formation of semicarbazones.
$(iii)$ During the preparation of esters from a carboxylic acid and an alcohol in the presence of an acid catalyst,the water or the ester should be removed as soon as it is formed.

Write chemical reactions to affect the following transformations:
$(i)$ Butan$-1-$ol to butanoic acid
$(ii)$ Benzyl alcohol to phenylethanoic acid
$(iii)$ $3-$Nitrobromobenzene to $3-$nitrobenzoic acid
$(iv)$ $4-$Methylacetophenone to benzene$-1,4-$dicarboxylic acid
$(v)$ Cyclohexene to hexane$-1,6-$dioic acid
$(vi)$ Butanal to butanoic acid.