Question

Which of the following has basicity 1?
(A) Acetic acid
(B) Nitric acid
(C) Hydrochloric acid
(D) All of the above

Answer 1

Hint: Find out what the term ‘basicity’ indicates. In each of the given acids, list the number of replaceable hydrogen atoms. Write the molecular formula of each of the given acids and find out how many protons they can donate. From the list, check which of the options have basicity 1 and then choose the correct option.


Complete step by step solution:
- Basicity is the property of acids to donate protons.
- Depending on the number of protons donated by an acid, it is classified as monobasic or dibasic or tribasic acids.
- A monobasic acid has basicity 1. That implies, the acid contains only one proton which can be donated. It is also known as monoprotic acid. For example, hydrochloric acid, HCl.
- A dibasic acid has basicity 2. This acid can donate two protons. For example, sulphuric acid, ${{H}_{2}}S{{O}_{4}}$.
- A tribasic acid has basicity 3. This acid can donate three protons. For example, phosphoric acid, ${{H}_{3}}P{{O}_{4}}$.
- In the question, we need to find which of the given acids are monobasic. Let’s take a look at them one by one.
(A) Acetic acid $\left( C{{H}_{3}}COOH \right)$ - Acetic acid has only one replaceable hydrogen atom. So, it is a monobasic acid.
(B) Nitric acid $\left( HN{{O}_{3}} \right)$ - Nitric acid also has only one replaceable hydrogen atom. So, it is a monobasic acid.
(C) Hydrochloric acid (HCl) – Hydrochloric acid also has only one replaceable hydrogen atom. So, it is also a monobasic acid.
- Therefore, all the acids have basicity 1.

- Therefore, the correct option is option (D).


Note: Don’t get confused with the term basicity. Basicity indicates the number of replaceable hydrogen atoms of one molecule of acid which can react with base. Acidity indicates the number of hydroxyl ions present in one molecule of base which can react with an acid.