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JEE Main levelOne or more correct optionsDifficulty 2 of 3bm193

Which statements about glycine are correct?

  1. AIn the solid state and in neutral water it exists as .
  2. BIts isoelectric point is the pH at which it exists entirely as the cation.
  3. CIt is amphoteric, reacting with both HCl and NaOH.
  4. DIts high melting point (about C with decomposition) is due to its ionic, salt-like zwitterionic lattice.

Answer: A, C, D

Glycine is a zwitterion with strong electrostatic attraction between molecules, hence the high mp and its salt-like lattice. It has both a basic -NH2/-NH3+ and acidic -COOH/-NH3+ character so it reacts with acids and bases. At the isoelectric point the dipolar (zwitterionic) form dominates, not the cation, so statement 2 is false.
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