$R + CH_3-CO-CH_3 \xrightarrow{H^{+}} \text{Schiff's base}$. What is $R$ in this reaction?

Arrange the following in the increasing order of their basic strengths: $CH_{3}NH_{2}$,$(CH_{3})_{2}NH$,$(CH_{3})_{3}N$,$NH_{3}$.

Aniline on treatment with a mixture of conc. $HNO_3$ and conc. $H_2SO_4$ yields:

Identify the products $y$ and $x$ in the following reaction sequence:
$C_6H_5CONH_2 \xrightarrow{NaOBr} y$
$C_6H_5CONH_2 \xrightarrow[(ii) H_3O^+]{(i) C_6H_5SO_2Cl / py, \Delta} x$

Which of the following compounds reacts with $HNO_2$ to form an alcohol?

Identify $B$ formed in the reaction: $Cl-(CH_2)_4-Cl$ $\xrightarrow{\text{excess } NH_3} A$ $\xrightarrow{NaOH} B + H_2O + NaCl$