Question

Which of the following monobasic acid?
(A). ${H_2}S{O_4}$
(B).$C{H_2}COOH$
(C). ${H_2}P{O_3}$
(D). ${H_2}C{O_3}$

Answer 1

Hint: A monobasic acid is the one that has only one replaceable hydrogen atom. For eq. $HCl,HF$ both of them are called monobasic acid as they have only one hydrogen atom that is replaceable. Whenever these acids are made to ionize in water they get ionized to give only one hydrogen ${{\text{H}}^{\text{ + }}}$ion.

Complete step by step answer:
What is the basicity of an acid? Basicity of an acid is the number of hydronium ions formed by one molecule of an acid in its aqueous solution.
The ionisable hydrogen atoms present in an acid represents its basicity.
Acid can be divided into following categories, On the basis of basicity:
(1). Monobasic acids
🡪 Where only one replaceable hydrogen atom is present
Example: $HCl,HBr$
(2). Dibasic acids
🡪 Where two ion is able hydrogens are three
E.g.${H_2}S{O_4}$ , oxalic acid
(3). Tribasic acids
🡪 Having three replaceable hydrogens
E.g. Phosphoric acid
(4). Tetrabasic acids
🡪 Having four ion is able hydrogen atom
E.g. Silicic acid
Now, coming to the options provided in the question:
(A). ${H_2}S{O_4}$🡪 it is dibasic acid, having two replaceable hydrogen atoms.
(B). $C{H_3}COOH$ 🡪 it is monobasic acid.
$C{H_3}COOH \to C{H_3}CO{O^ - } + {H^ + }$
It gives one hydronium ion after ionisation.
(C).$$

Three are three hydrogens in ${H_3}P{O_3}$ but its basicity is two. So, it is dibasic acid.
(D). ${H_2}C{O_3}$ 🡪 It is also a dibasic acid.

So, the correct answer is Option B.

Note: It should be noted that the number of hydrogen atoms present in an atom is not known as basicity as not all hydrogen are ionisable . Only those hydrogens are ionisable that are directly bonded with oxygen as in the case of ${H_3}P{O_3}$ .