The gas evolved when ethyl amine reacts with sodium metal is

The major product $(R)$ of the following reaction is:
$C_6H_5NH_2$ $\xrightarrow[{0 \, ^\circ C}]{{HNO_2}} P$ $\xrightarrow{{HBF_4}} Q$ $\xrightarrow[{Cu, \, \Delta }]{{NaNO_2}} R$

On heating benzyl amine with chloroform and ethanolic $KOH$,the product obtained is:

An organic compound $(C_3H_9N)$ $(A)$,when treated with nitrous acid,gave an alcohol and $N_2$ gas was evolved. $(A)$ on warming with $CHCl_3$ and caustic potash gave $(C)$ which on reduction gave isopropylmethylamine. Predict the structure of $(A)$.

If aniline is treated with a $1:1$ mixture of conc. $HNO_{3}$ and conc. $H_{2}SO_{4}$,$p$-nitroaniline and $m$-nitroaniline are formed in nearly equal amounts. This is due to:

Arrange the following in increasing order of basicity: $CH_3NH_2$,$(CH_3)_2NH$,$C_6H_5NH_2$,$(CH_3)_3N$.