
${C_6}{H_5} - N{H_2}\xrightarrow[{HCl}]{{NaN{O_2}}}A\xrightarrow{{CuCN}}B\xrightarrow{{{H_2}/Ni}}C\xrightarrow{{HN{O_2}}}D$
product $(D)$ would be
What is $''B''$ ?
$\xrightarrow{{SOC{l_2}}}B\xrightarrow{{N{H_3}}}C\xrightarrow[{B{r_2}}]{{NaOH}}D$

$(i)$ Hinsberg test
$(ii)$ Carbyl amine test
$(iii)$ Hofmann mustard oil test
$(iv)$ $HNO_2$ test