Which of the following amino acids is not optically active?

Which of the following $\alpha-$amino acids does not contain a chiral carbon?

Which of the following reagents gives a blue colour with proteins?

What is the molecular weight of a protein?

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

Assume that a particular amino acid has an isoelectric point of $6.0$. In a solution at $pH$ $1.0$,which of the following species will predominate?