The ionization state of amino acids is altered by a change in ph. at low ph, near the p k a pka for the carboxylic acid, the − cooh −cooh proton is lost from the fully protonated form. as the ph approaches physiological levels, the zwitterionic form predominates. at high ph, near the p k a pka for the amino group, one of the − nh + 3 −nh3+ protons is lost to form the fully deprotonated species.

The pH at which amino acid would not have net charge is 6

From the graph , it is obvious that zwitterion form that carries no net charge of amino acid exist at pH 4 to 8 .

The Pink line shows the ionisation of carboxylic acid and green line shows ionisation of ammonium ion .

pH at which none of the green and pink line exist is the pH where complete zwitterion form exist ( having no net charge ) .

So, pH 6 is the correct answer .

Explanation:

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