Question

Which of the following is an amphoteric acid?
A.Glycine
B.Salicylic acid
C.Benzoic acid
D.Citric acid

Answer 1

In the given question we have to observe that all of the options are acids. Now we know that to have the amphoteric nature you need to have the characteristic of having both the reactions with the bases and the acids. So among these first we have to make the formulas for them then we can see which one also has the basic nature, which in this case is the Glycine.

Complete step by step answer:
Option $1$ : The first option is the Glycine. The structure of the Glycine is ${H_2}N - C{H_2} - COOH$ .

Option $2$ : The second option is the Salicylic Acid. The structure of the Salicylic Acid is ${C_6}{H_4}\left( {OH} \right)COOH$

Option $3$ : The third option is the Benzoic Acid. The structure of the Benzoic Acid is ${{\mathbf{C}}_6}{H_5}COOH$

Option $4$ : The fourth option is the Citric Acid. The structure of the Citric Acid is ${C_6}{H_8}{O_7}$
Now for any compound to be amphoteric it should have the capability of reacting with both the acids and the bases. So among the given options we can say that Salicylic Acid, Benzoic Acid and the Citric Acid all just shows the acidic nature.

But Glycine has both the basic nitrogen component and the carboxylic acid component therefore it shows both the nature. So it would be the answer.
Hence the correct option is option A, Glycine.

Note: Glycine is an amino acid that has a single hydrogen atom as its side chain. It is one of the simplest amino acids (since carbamic acid is unstable), with the chemical formula ${H_2}N - C{H_2} - COOH$ . Glycine is one of the proteinogenic amino acids