(a)
$CH_{3}CH_{2}NH_{2}\overset{NaNO_{2} + HCl\ \ \ }{\rightarrow}CH_{3}\ CH_{2}\ OH + N_{2}\ + H_{2}O + NaCl$
Ethylamine
$NH_{2}CONH_{2}\overset{NaNO_{2} + HCl\ \ \ }{\rightarrow}2N_{2} + H_{2}O + CO_{2} + NaCl$
Urea
$CH_{3}CONH_{2}\overset{NaNO_{2} + HCl\ \ \ }{\rightarrow}CH_{3}\ COOH + N_{2}\ + H_{2}O + NaCl$
Acetamide
$C_{6}H_{5}NH_{2}\overset{NaNO_{2} + HCl\ \ \ }{\rightarrow}C_{6}H_{5}N_{2}^{+}Cl^{-}H_{2}O + NaCl$
Aniline