The number of amino acids and number of peptide bonds in a linear tetrapeptide (made of different amino acids) are respectively

The value of $x$ in compound '$D$' is $.........$.

$A$ protein undergoes reversible thermal denaturation from its initial state $N$ to denatured state $D$ according to $N \rightleftharpoons D$. At $60 ^\circ C$, the concentrations of both $N$ and $D$ are equal at equilibrium, and the standard enthalpy change of denaturation is $666 \text{ kJ mol}^{-1}$. The standard entropy change ($\Delta S^\circ$ in $\text{kJ K}^{-1} \text{mol}^{-1}$) of the protein upon denaturation at $60 ^\circ C$ is closest to

Which is an optically inactive amino acid?

Which of the following will not give a purple color with ninhydrin?

Match List-$I$ with List-$II$.

List-$I$ (Natural amino acid)	List-$II$ (Code)
$A$. Glutamic acid	$I$. $Q$
$B$. Glutamine	$II$. $W$
$C$. Tyrosine	$III$. $E$
$D$. Tryptophan	$IV$. $Y$