Question

Which one is dibasic acid?
A.HCl
B.${H_2}S{O_4}$
C.$\;{H_3}P{O_4}$
D.All of the above

Answer 1

First of all, acid is classified into – monobasic, dibasic, tribasic etc. Since., the general property of acid is mainly due to the presence of hydrogen in them and not a single acid can exist without the presence of hydrogen atom. So, the basicity of the acid depends on the number of ionisable hydrogen atoms.

Complete answer:
Basicity of an acid is defined as the number of ionizable hydrogen ions present in one molecule of an acid is called basicity.
Based on the basicity acids were classified into different types. They are of following types:
Mono-basic acids: The acids which on ionisation produces one hydronium ion in water are known as mono-basic acids.
Examples are: Hydrochloric acid (HCl), Hydrobromic acid
Di-basic acids: The acids which on ionisation produces two hydronium ions or which has two acidic hydrogen atoms in its molecules are known as di-basic acids.
Examples are sulphuric acid (${H_2}S{O_4}$), Carbonic acid ($\;{H_3}P{O_4}$) etc.
${H_2}S{O_{4(aq)}} \to 2{H^ + }\; + HS{O_4}^ -$
Basicity of ${H_2}S{O_4}$ is 2.
Tribasic acids: The acids which on ionisation produces three hydronium ions are called astri-basic acids.
Example: Orthophosphoric acid ($\;{H_3}P{O_4}$), ${H_3}P{O_3}$..etc
So, sulphuric acid (${H_2}S{O_4}$) is a dibasic acid.

Therefore, the correct answer is option (B).

Note:
We should note that it is not in all cases that a compound furnishes all its containing hydrogen atoms as ions. Example, in ethanoic acid. When 1 mole of hydrogen ions is furnished from 1 mole of an acid, the acid is monobasic; it is dibasic when 2 moles of hydrogen ions are furnished, and tribasic when 3 moles of hydrogen ions are furnished from 1 mole of its solution.