`H_(3)PO_(3)` is ..... acid

Options

A. Monobasic
B. Dibasic
C. Tribasic
D. None

Explanation

To determine the type of acid H₃PO₃ is, we need to analyze its structure and the number of replaceable hydrogen ions (H⁺) it has. Here’s a step-by-step solution:

### Step 1: Understand Basicity
Basicity refers to the number of hydrogen ions (H⁺) that can be replaced by a base in an acid. In simpler terms, it is the number of replaceable hydrogen atoms in the acid.

### Step 2: Analyze the Structure of H₃PO₃
H₃PO₃, also known as phosphorous acid, has the following structure:
- It contains one phosphorus (P) atom.
- It has three hydrogen (H) atoms.
- It has one double bond with oxygen (O) and one hydroxyl group (–OH).

### Step 3: Identify Replaceable Hydrogen Atoms
In H₃PO₃:
- The hydrogen atom directly bonded to the phosphorus atom is not replaceable because it is non-polar and does not ionize.
- The two hydrogen atoms that are part of the hydroxyl groups (–OH) are the ones that can be replaced by a base.

### Step 4: Count the Replaceable Hydrogens
Since there are two hydrogen atoms attached to the oxygen (–OH) groups, these are the replaceable hydrogen ions. Therefore, the basicity of H₃PO₃ is 2.

### Step 5: Classify the Acid
Based on the basicity:
- An acid with one replaceable hydrogen is called monobasic.
- An acid with two replaceable hydrogens is called dibasic.
- An acid with three replaceable hydrogens is called tribasic.

Since H₃PO₃ has 2 replaceable hydrogen ions, it is classified as a dibasic acid.

### Final Answer
H₃PO₃ is a dibasic acid.

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