Question

An acid having basicity of one and having only one replaceable hydrogen ion per molecule of acid:
A.Carbonic acid
B.Nitric acid
C.Sulphuric acid
D.Hydrochloric acid

Answer 1

Basicity and number of replaceable hydrogens of a molecule is the number of ${H^ + }$ ions removed when acid is mixed with water. Mainly all hydrogens are removed from acid and converted into ${H^ + }$ ions and the remaining part also an ion with negative charge which is equal to the number of replaceable hydrogen.

Complete step by step answer:
Carbonic acid $\left( {{H_2}C{O_3}} \right)$ is ionic in nature and there are two ${H^ + }$ ions and one $C{O_3}^{2 - }$ ion are combined to form carbonic acid then basicity of carbonic acid is 2 because it has two replaceable ${H^ + }$ ions.
Nitric acid $\left( {HN{O_3}} \right)$ also ionic in nature and formed from one ${H^ + }$ ion and one $N{O_3}^ -$ ion. Then it has one replaceable hydrogen and its basicity is one.
Sulphuric acid $\left( {{H_2}S{O_4}} \right)$ gives two ${H^ + }$ ions and one $S{O_4}^{2 - }$, two ${H^ + }$ ions can be removed when water is added in it then its basicity is two and number of replaceable ions are also two.
Hydrochloric acid $\left( {HCl} \right)$ is formed from one ${H^ + }$ ion and one $C{l^ - }$ ion. Then it has one replaceable hydrogen and its basicity is one.
Then there are two acids having basicity of one and having only one replaceable hydrogen ion per molecule of acid that are nitric acid and hydrochloric acid.
Hence the correct answer is options B and D.

Note: Similar to basicity of acids, the acidity of bases is equal to the number of replaceable hydroxide ions $\left( {O{H^ - }} \right)$ per molecule of base. Acidity and basicity also represent the valency of ions formed after removing ${H^ + }$ ions or $O{H^ - }$ ions from the compound.