Which of the following is the most basic compound?

If aniline is treated with conc. $H_{2}SO_{4}$ and heated at $200^{\circ}C$,the product is

The conversion of $A$ to $B$ is an example of which reaction?
$\text{Propanenitrile}$ $\xrightarrow{LiAlH_4} A$ $\xrightarrow{CHCl_3 / \text{alcoholic } KOH, \Delta} B$

Which of the following products is a Schiff base?
$C_2H_5NH_2 \xrightarrow{HNO_2} a$
$C_2H_5NH_2 \xrightarrow{C_6H_5CHO} b$
$C_2H_5NH_2 \xrightarrow{NOCl} c$
$C_2H_5NH_2 \xrightarrow{C_6H_5SO_2Cl} d$

In which of the following reactions is a primary amine not obtained as a product?

$A$ student has been given a compound $x$ of molecular formula $C_6H_7N$. $x$ is sparingly soluble in water. However,on addition of dilute mineral acid,$x$ becomes soluble in water. $x$ when treated with $CHCl_3$ and $KOH$ (alc.) produces $y$. $y$ has a specific unpleasant smell. On treatment with benzenesulphonyl chloride,$x$ gives a compound $z$ which is soluble in alkali. The number of different $H$ atoms present in $z$ is: