Question

Basicity of acetic acid is:
A) 4
B) 3
C) 1
D) 2

Answer 1

Hint: The basicity of an acid is the number of replaceable hydrogen atoms present in an acid. To find the basicity of an acid, you should know the chemical formula of acetic acid and it is $C{H_3}COOH$. Do the ionization reaction of acetic acid and find the number of hydrogen atoms produced by it.

Complete step by step answer:
Basicity of an acid is defined as the number of replaceable hydrogen atoms present in the molecule of an acid or we can also say that number of hydrogen atoms produced by an acid on ionization.
Here, in the question, we are asked to find the basicity of acetic acid. The chemical formula of acetic acid is $C{H_3}COOH$. Let us do ionization of acetic acid. The chemical equation will be represented as:
$C{H_3}COOH \rightleftharpoons C{H_3}CO{O^ - } + {H^ + }$
Thus, on ionization of acetic acid, we get one hydrogen ion (${H^ + }$) or acetic acid contains only one replaceable hydrogen atom. Hence, clearly the basicity-A of acetic acid is 1.
Therefore, option C is the correct answer.
Additional information: The acid which contains one replaceable hydrogen atom in its molecule is called monobasic acid. Thus, acetic acid ($C{H_3}COOH$) is monobasic. The acid which contains two replaceable hydrogen atoms in its molecule is called dibasic acid whereas the acid which contains three replaceable hydrogen atoms in its molecule is called tribasic acid.

Note: Acetic acid is a weak acid and thus, it dissociates partially in water. Its ions upon dissociation remain in equilibrium with each other. The dissociation or ionization reaction of acetic acid in water can also be represented as:
$C{H_3}COOH + {H_2}O \rightleftharpoons C{H_3}CO{O^ - } + {H_3}{O^ + }$
 ${H_3}{O^ + }$ (hydronium ion) is nothing but proton, ${H^ + }$. Acetic acid is also known as monoprotic acid.