$CH_3-CH_2-NH_2 \xrightarrow{CHCl_3, KOH} \text{Product}$

Arrange the following in decreasing order of their $pK_{b}$ values:

What is the correct order of basic strength for $NH_3$,$CH_3NH_2$,and $(CH_3)_2NH$?

Aniline reacts with mixed acid (conc. $HNO_3$ and conc. $H_2SO_4$) at $288 \ K$ to give $P$ $(51 \%)$,$Q$ $(47 \%)$ and $R$ $(2 \%)$. The major product$(s)$ of the following reaction sequence is (are):
$R$ $\xrightarrow[2) Br_2, CH_3CO_2H]{1) Ac_2O, \text{pyridine}}$ $\xrightarrow{3) H_3O^+}$ $\xrightarrow{4) NaNO_2, HCl / 273-278 \ K}$ $\xrightarrow{5) EtOH, \Delta}$ $\xrightarrow{6) Sn/HCl}$ $\xrightarrow{7) Br_2/H_2O \text{ (excess)}} \text{Major Product}$

When aniline is nitrated with nitrating mixture in ice-cold condition, the major product obtained is

Which of the following compounds gives an even number of Hoffmann's exhaustive methylation and elimination cycles?