COMEDK202510 May 2025Morning ShiftChemistryBiomoleculesActual
Two statements, one Assertion (A) and the other Reason (R) are given. Choose the correct option. Assertion: 2-aminoethanoic acid and p-aminobenzene sulphonic acid can exist as Zwitter ions while p-aminobenzoic acid cannot. Reason: When the acid group is a relatively strong proton donor and the - NH ₂ group is sufficiently basic it can accept a H ⁺ ion from the acid group to form the dipolar ion.
Options
- ABoth A and R are correct but R is not the correct explanation of A .
- BBoth A and R are correct and R is the correct explanation of A .
- CA is correct but R is wrong.
- DA is wrong but R is correct.
Correct answer
B. Both A and R are correct and R is the correct explanation of A .
Step-by-step solution
A Zwitter ion is formed when an acidic group (proton donor) and a basic group (proton acceptor) are present in the same molecule, allowing for internal proton transfer. 2-aminoethanoic acid (glycine) contains a carboxylic acid group ( -COOH ) and an amino group ( -NH₂ ), which allows it to exist as H₃N⁺-CH₂-COO⁻ . p-aminobenzene sulphonic acid (sulphanilic acid) contains a strongly acidic sulphonic acid group ( -SO₃H ) and a basic amino group ( -NH₂ ), which allows it to exist as a Zwitter ion H₃N⁺-C₆H₄-SO₃⁻ . p-am