Which amino acid does not contain a chiral centre?

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 $(HNO_2)$.

Which of the following proteins destroys the antigen when it enters a body cell?

$A$ protein '$X$' with a molecular weight of $70,000 \ u$,on hydrolysis gives amino acids. One of these amino acids is:

The number of essential and non-essential amino acids from the following list respectively is:
Val,Gly,Leu,Lys,Pro,Ser

In $\text{alanyl-glycyl-leucyl-alanyl-valine}$,the number of peptide linkages is $......$