JEE Advanced 2020 Full Test 7 Paper 2

The isoelectric point (pHi) is the pH at which the amino acid exists only as a dipolar ion with net charge zero.
At isoelectric point, for a neutral amino acid, pHi=‌

(pKa1+pKa2)

2

The dissociation of cationic form of valine can be represented as

The species with zero net charge exists between species with (+1) and (-1) net charges.
pHi=‌

(pKa1+pKa2)

2

=‌

9.69+2.31

2

=6
When the pH of the solution equals to pHi, the structure of valine is
When the pH of the solution is two, the structure of valine is
When the pH of the solution is 12, the structure of valine is