The major product $(A)$ formed in the following reaction sequence is:

Which is the correct decreasing order of basic strength for the following compounds?
$(I)$ Aniline
$(II)$ $p$-Nitroaniline
$(III)$ $p$-Cyanoaniline
$(IV)$ $p$-Toluidine

Identify the product $Y$ in the following sequence of reactions.

Identify the alkene obtained as the major product in the following Hofmann elimination reaction.
$(CH_3CH_2CH_2)N^{+}(CH_2CH_3)_3 I^{-}$ $\xrightarrow[\Delta]{\text{moist } Ag_2O} A$ $\xrightarrow[\Delta]{\text{heat}} \text{Alkene} + \text{Amine}$

$A$ 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:

An organic compound $[A]$ $(C_4H_{11}N)$ shows optical activity and gives $N_2$ gas on treatment with $HNO_2$. The compound $[A]$ reacts with $PhSO_2Cl$ producing a compound which is soluble in $KOH$. The structure of $A$ is: