The end product $C$ of the following reaction is $C_2H_5NH_2$ $\xrightarrow{HNO_2} A$ $\xrightarrow{PCl_5} B$ $\xrightarrow{NH_3 (alc.)} C$

Consider the following sequence of reactions to produce major product $(A)$. Molar mass of product $(A)$ is $........... \ g \ mol^{-1}$. (Given molar mass in $g \ mol^{-1}$ of $C : 12, H : 1, O : 16, Br : 80, N : 14, P : 31$)

$A$ student has planned to prepare acetanilide from aniline using acetic anhydride. The student has started from $9.3 \ g$ of aniline. However, the student has managed to obtain $11 \ g$ of dry acetanilide. The $\%$ yield of this reaction is $.....$ (in $\%$)

The correct order of basic strengths of the given amines is:

What are $X$ and $Y$ respectively in the following set of reactions?

Amongst the compounds given,the one that would form a brilliant colored dye on treatment with $NaNO_2$ in dil. $HCl$ followed by addition to an alkaline solution of $\beta$-naphthol is