A tribasic acid with peroxy bond is

Options

A. `H_(3)PO_(2)`
B. `H_(3)PO_(3)`
C. `H_(3)PO_(4)`
D. `H_(3)PO_(5)`

Answer

To find the tribasic acid with a peroxy bond, we need to analyze the options given and determine which one meets the criteria of being tribasic and containing a peroxy bond.

### Step-by-Step Solution:

1. **Understanding Basicity**:
- Basicity of an acid refers to the number of replaceable hydrogen atoms. For a tribasic acid, the basicity must be 3, meaning it can donate three protons (H⁺ ions).

2. **Identifying Peroxy Bond**:
- A peroxy bond is characterized by an oxygen-oxygen single bond (O-O). This bond is essential for the acid we are looking for.

3. **Analyzing the Options**:
- We will analyze the given options one by one to check their basicity and the presence of a peroxy bond.

4. **Option 1: H₃PO₂**:
- Structure: H₃PO₂ has one double bond with oxygen and one hydroxyl group (OH) attached to phosphorus.
- Basicity: 1 (only one replaceable hydrogen).
- Conclusion: Not tribasic, so this option is incorrect.

5. **Option 2: H₃PO₃**:
- Structure: H₃PO₃ has a phosphorus atom with one double bond to oxygen and two hydroxyl groups.
- Basicity: 2 (two replaceable hydrogens).
- Conclusion: Not tribasic, so this option is incorrect.

6. **Option 3: H₃PO₄**:
- Structure: H₃PO₄ has a phosphorus atom with one double bond to oxygen and three hydroxyl groups.
- Basicity: 3 (three replaceable hydrogens).
- Conclusion: It is tribasic but does not contain a peroxy bond, so this option is incorrect.

7. **Option 4: H₃PO₅**:
- Structure: H₃PO₅ has a phosphorus atom with one double bond to oxygen, three hydroxyl groups, and an O-O bond (peroxy bond).
- Basicity: 3 (three replaceable hydrogens).
- Conclusion: This compound is tribasic and contains a peroxy bond, making it the correct answer.

### Final Answer:
The tribasic acid with a peroxy bond is **H₃PO₅**.