Predict the major product $(A)$ for the following reaction:

Which among the following amines has the lowest $pK_{b}$ value?

Aniline in a set of reactions yielded a product $D$. The structure of product $D$ would be:
Aniline $\xrightarrow{NaNO_2/HCl} A$ $\xrightarrow{CuCN} B$ $\xrightarrow{H_2/Ni} C$ $\xrightarrow{HNO_2} D$

Which of the following would produce an alcohol on treatment with $NaNO_2$ and $HCl$ in the presence of water?

Unpleasant smelling carbylamines are formed by heating alkali and chloroform with

Identify compound $X$ in the following reaction.