At the isoelectric pH of an amino acid which has two pKa values the net charge is

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Quizplus · Accepted Answer

The isoelectric pH is the pH at which an amino acid has a net charge of zero. If an amino acid has two pKa values, one for the carboxyl group (-COOH) and one for the amino group (-NH2), then at the isoelectric pH, both groups are in their zwitterionic (neutral) form. This occurs when the pH is equal to the average of the two pKa values. Since there are equal numbers of charged -COO- and +NH3 groups, the net charge is zero. Therefore, the answer is C.

At the Isoelectric PH of an Amino Acid Which Has