Optically inactive amino acid is :-

Within the list shown below, the correct pair of structures of alanine in $pH$ ranges $2-4$ and $9-11$ is:
$I$. $H_{3}N^{+}CH(CH_{3})COOH$
$II$. $H_{2}NCH(CH_{3})COO^{-}$
$III$. $H_{3}N^{+}CH(CH_{3})COO^{-}$
$IV$. $H_{2}NCH(CH_{3})COOH$

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

Which of the following amino acids is basic in nature?

Which statement is correct for the protein hemoglobin?

The number of $sp^2$ hybridised carbons present in "Aspartame" is