Which of the following statements are true A. Water solubility of an amino

Question

Which of the following statements are true
A. Water solubility of an amino acid is maximum at a pH when concentrations of anions and cations are equal.
B. Amino acids can be detected by ninhydrin test
C. On reacting with nitrous acid amino acids release

N_{2}

Options:

A . All

B . B and C

C . A and B

D . only A

Answer: Option B
:
B
Amino acids can form zwitter ions, that isa molecule or ion having separate positively and negatively charged groups. Amino acids form due to the presence of an amine group, that can ionize to form

{N H}_{3}^{+}

and a carboxyl group that can form

{C O O}^{-}

. When they are in the zwitter ion form, they do not migrate in an electric field and they precipitate out of the solution. Therefore amino acids are least soluble at a pH when they exist in the zwitter ion form, that is when the concentration of anions and cations are equal.
The other two statements are true:
The amine group of amino acids reacts with ninhydrin reagent to give a purple colour complex.
And amino acids react with nitrous acid releasing