Write the reactions of $(i)$ aromatic and $(ii)$ aliphatic primary amines with nitrous acid.

$(i)$ Aromatic primary amines react with nitrous acid (prepared in situ from $NaNO_2$ and a mineral acid such as $HCl$) at $273-278 \, K$ to form stable aromatic diazonium salts.
$C_6H_5NH_2 + HNO_2 + HCl \xrightarrow{273-278 \, K} [C_6H_5N_2^+Cl^-] + 2H_2O$
$(ii)$ Aliphatic primary amines react with nitrous acid to form unstable aliphatic diazonium salts,which decompose to produce alcohols and $HCl$ with the evolution of $N_2$ gas.
$R-NH_2 + HNO_2$ $\xrightarrow{NaNO_2 + HCl} [R-N_2^+ Cl^-]$ $\xrightarrow{H_2O} ROH + N_2 \uparrow + HCl$