Question

Alanine forms Zwitter ion which exists as

• A. A
• B. B
• C. C
• D. D

Hint:

Amino acids exist as zwitter ions near their isoelectric pH.

Answer 1

The Correct Option is B

Step 1: Formula / Definition}
\[ \text{Zwitter ion} = \text{Dipolar ion with } \mathrm{NH_3^+} \text{ and } \mathrm{COO^-} \]
Step 2: Calculation / Simplification}
Zwitter ion exists at isoelectric point (around pH \(\approx 6\)).
Among the given options, pH = 4 is closest to the condition where dipolar ion form is significant.
Thus, alanine exists predominantly as zwitter ion in this medium.
Step 3: Final Answer
\[ \text{Option (B)} \]