MixedHardQuestion 870013
Question
A Zwitter ion (amphoteric species) of an amino acid forms at:
- AIsoelectric point (pI) where net charge = 0Correct
- BHigh pH only
- CLow pH only
- DAll pH values
Correct answer
Isoelectric point (pI) where net charge = 0
Explanation
At the isoelectric point (pI), an amino acid exists predominantly as the zwitterion (NH₃⁺/COO⁻) with zero net charge. Below pI: cationic (NH₃⁺/COOH). Above pI: anionic (NH₂/COO⁻). Zwitterions have minimum solubility at pI.