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Which of the following compounds can form a zwitterion?
Explanation
An amino acid has both $-NH_2$ and $-COOH$ groups, giving a dipolar ion.
Detailed Solution
$H_3\overset{+}{N}-CH_2-COOH \rightleftharpoons H_3\overset{+}{N}-CH_2-COO^-$ (zwitterion form) $\rightleftharpoons H_2N-CH_2-COO^-$
$pK_a$ values: $-\overset{+}{N}H_3$ = 9.60, $-COOH$ = 2.34
Glycine contains both an acidic and a basic group, so it forms a zwitterion.