Which of the following molecules is capable of forming Zwitter ion?

Step-by-step solution

A Zwitter ion is a dipolar ion formed by the internal transfer of a proton from an acidic group to a basic group within the same molecule. Among the given options, NH ₂ CH ₂ COOH (glycine) is an amino acid that contains both an acidic carboxyl group ( - COOH ) and a basic amino group ( - NH ₂ ). In aqueous solution, the - COOH group donates a proton to the - NH ₂ group, forming the Zwitter ion ⁺ NH ₃ CH ₂ COO ⁻ . The other molecules lack either an acidic or a basic group required for this internal proton transfer.