Which among the following has the highest basic strength?

The given reaction is $2$-methylbutanamide reacting with $KOBr$ and $\Delta$. What is the correct statement about the product?

Consider the following sequence of reactions: $C_2H_5-Br$ $\xrightarrow{AgCN} A$ $\xrightarrow{H_2/Ni} B$. Product $B$ is:

$A$ solution contains $1 \ g \ mol$ each of $p-$toluene diazonium chloride and $p-$nitrophenyl diazonium chloride. To this,$1 \ g \ mol$ of alkaline solution of phenol is added. Predict the major product and explain your answer.

The correct statement regarding the basicity of arylamines is

What is the major product formed when ethylamine reacts with carbon disulfide $(CS_2)$ in the presence of mercuric chloride $(HgCl_2)$?