How many of these acids are monobasic in nature?
`H_(2)S, H_(2)O_(2), HCOOH,H_(3)BO_(3),H_(3)PO_(2), HXO_(4), Ph-SO_(3)H`

Answer

To determine how many of the given acids are monobasic in nature, we will analyze each acid one by one and identify its basicity, which is the number of replaceable hydrogen ions (H⁺) it can donate.

1. **H₂S (Hydrogen Sulfide)**:
- H₂S can dissociate into 2 H⁺ ions and S²⁻.
- Basicity = 2 (Dibasic)

2. **H₂O₂ (Hydrogen Peroxide)**:
- H₂O₂ can also release 2 H⁺ ions.
- Basicity = 2 (Dibasic)

3. **HCOOH (Formic Acid)**:
- HCOOH dissociates to give 1 H⁺ and HCOO⁻.
- Basicity = 1 (Monobasic)

4. **H₃BO₃ (Boric Acid)**:
- H₃BO₃ reacts with water to release 1 H⁺ ion.
- Basicity = 1 (Monobasic)

5. **H₃PO₂ (Phosphorous Acid)**:
- H₃PO₂ has one replaceable H⁺ ion.
- Basicity = 1 (Monobasic)

6. **HXO₄ (where X is a halogen)**:
- HXO₄ can dissociate to give 1 H⁺ ion.
- Basicity = 1 (Monobasic)

7. **Ph-SO₃H (Benzene Sulfonic Acid)**:
- Ph-SO₃H can dissociate to give 1 H⁺ ion.
- Basicity = 1 (Monobasic)

Now, let's summarize the basicities:
- H₂S: Dibasic (2)
- H₂O₂: Dibasic (2)
- HCOOH: Monobasic (1)
- H₃BO₃: Monobasic (1)
- H₃PO₂: Monobasic (1)
- HXO₄: Monobasic (1)
- Ph-SO₃H: Monobasic (1)

**Total Monobasic Acids**:
- HCOOH + H₃BO₃ + H₃PO₂ + HXO₄ + Ph-SO₃H = 5 Monobasic Acids

Therefore, the answer is **5** monobasic acids.