Which synthesis was done by Stanley Miller?

The amino acid which is not optically active is

Choose the peptide that matches the abbreviation $Phe-Val-Ala$.

The general structural formula of $\alpha$-amino acid is $NH_2-CH(R)-COOH$. The group $R$ in tryptophan $(X)$ and histidine $(Y)$ are respectively:

Which of the following statements is/are true for amino acids?
$(A)$ The solubility of an amino acid in water is maximum at its isoelectric point $(pH)$.
$(B)$ It gives a ninhydrin test.
$(C)$ It releases nitrogen gas upon reaction with nitrous acid $(HNO_2)$.

The Zwitter ion among the following is