Aniline reacts with acetaldehyde to form

In the following reaction sequence,$C_2H_5NH_2$ $\xrightarrow{HNO_2} A$ $\xrightarrow{PCl_5} B$ $\xrightarrow{NH_3} C$,the compound '$C$' is

The correct order of nucleophilicity is $.....$ .

Which of the following is the correct order for basic strength?

$A$ compound of molecular weight $180$ is acetylated to give a compound of molecular weight $390$. The number of amino groups in the initial compound is:

The major product of the reaction is: