$(a)$ Methionine $(b)$ Isoleucine
$(c)$ Valine $(d)$ Cysteine
$\begin{align}
\begin{matrix}
C{{H}_{3}}-CH-C{{O}_{2}}H \\
|\,\,\,\,\,\,\,\, \\
\underset{\oplus }{\mathop{N}}{{H}_{3}} \\
\end{matrix}\,\,\,\,\,\,p{{K}_{a}}=2.2 \\
\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,p{{K}_{b}}=4.4 \\
\end{align}$
$\begin{array}{|c|c|c|c|}\hline {} &\text { Molisch's Test} & {\text { Barfoed Test}} & {\text { Biuret Test}} \\ \hline \text { A} & { Positive } & {\text { Negative }} & {\text { Negative }} \\ \hline \text { B } & {\text { Positive }} & {\text { Positive }} & {\text { Negative }} \\ \hline \text { C } & {\text { Negative }} & {\text { Negative }} & {\text { Positive }} \\ \hline\end{array}$
$A, B$ and $C$ are respectively
| List $I$ (Natural amino acid) | List $II$ (Code) |
| $A$ Glutamic acid | $I$ $Q$ |
| $B$ Glutamine | $II$ $W$ |
| $C$ Tyrosine | $III$ $E$ |
| $D$ Tryptophan | $IV$ $Y$ |
(image) $\xrightarrow{{B{r_2}/{H_2}O}}$ product