Question

Which of the following gives the correct representation of zwitter ion of the given amino acid ?

• A.

  

• B.

  

• C.

  

• D.

  

Hint:

In a zwitter ion the -COOH proton moves to the -NH2, giving -COO(-) and -NH3(+) in one molecule.

Answer 1

The Correct Option is B

Step 1: Define the target.
A zwitter ion has one positive and one negative charge on different atoms of the same molecule, so the net charge is zero.

Step 2: Use charge counting.
Count the charges on the right side of each option. Option 1 has no charged group. Option 3 has only a minus, net -1. Option 4 has only a plus, net +1. Option 2 has one plus and one minus, net 0.

Step 3: Check the proton count.
In option 2 the NH2 gained one H and the COOH lost one H. The total number of hydrogens stays the same, so it is the same compound in a different form. This is a proper internal acid-base change.

Final Answer:
Only option (2) shows a neutral molecule carrying both charges. \[ \boxed{\text{Option (2)}} \]