Which of the following reagents is used in the Hoffmann elimination reaction of amines?

The reaction of ethylamine and acetic anhydride leads to the formation of:

When ethyl amine is heated with chloroform and alcoholic $KOH$,a compound with an offensive smell is obtained. This compound is

Which of the following compounds is most basic?

Compare the basic strengths of the given compounds:

Isomeric amines with molecular formula $C_8H_{11}N$ give the following tests:
Isomer $(P) \Rightarrow$ Can be prepared by Gabriel phthalimide synthesis.
Isomer $(Q) \Rightarrow$ Reacts with Hinsberg's reagent to give a solid insoluble in $NaOH$.
Isomer $(R) \Rightarrow$ Reacts with $HONO$ followed by $\beta$-naphthol in $NaOH$ to give a red dye.
Isomers $(P), (Q)$ and $(R)$ respectively are: