How many of these acids are monobasic here?
`H_(3)PO_(2), H_(3)PO_(3), H_(2)CO_(3), H_(2)SO_(4), H_(2)S_(2)O_(4), H_(2)CrO_(4), H_(3)BO_(3), HNO_(2)`

Answer

To determine how many of the given acids are monobasic, we need to analyze each acid and count the number of replaceable hydrogen ions (H⁺) they contain. An acid is classified as monobasic if it can donate one proton (H⁺) per molecule.

Let's analyze each acid one by one:

1. **H₃PO₂ (Phosphorous acid)**:
- Structure: H₃PO₂ has one hydroxyl group (–OH) and two hydrogen atoms attached to phosphorus.
- Replaceable H⁺: It can donate 1 H⁺ (the one from the –OH group).
- **Classification**: Monobasic.

2. **H₃PO₃ (Phosphoric acid)**:
- Structure: H₃PO₃ has two hydroxyl groups (–OH) and one hydrogen atom attached to phosphorus.
- Replaceable H⁺: It can donate 2 H⁺ (one from each of the two –OH groups).
- **Classification**: Dibasic.

3. **H₂CO₃ (Carbonic acid)**:
- Structure: H₂CO₃ has two hydroxyl groups (–OH) and can donate two protons.
- Replaceable H⁺: It can donate 2 H⁺.
- **Classification**: Dibasic.

4. **H₂SO₄ (Sulfuric acid)**:
- Structure: H₂SO₄ has two hydroxyl groups (–OH) and can donate two protons.
- Replaceable H⁺: It can donate 2 H⁺.
- **Classification**: Dibasic.

5. **H₂S₂O₈ (Peroxydisulfuric acid)**:
- Structure: H₂S₂O₈ has two hydroxyl groups (–OH) and can donate two protons.
- Replaceable H⁺: It can donate 2 H⁺.
- **Classification**: Dibasic.

6. **H₂CrO₄ (Chromic acid)**:
- Structure: H₂CrO₄ has two hydroxyl groups (–OH) and can donate two protons.
- Replaceable H⁺: It can donate 2 H⁺.
- **Classification**: Dibasic.

7. **H₃BO₃ (Boric acid)**:
- Structure: H₃BO₃ has three hydroxyl groups (–OH) but can only donate one proton.
- Replaceable H⁺: It can donate 1 H⁺.
- **Classification**: Monobasic.

8. **HNO₂ (Nitrous acid)**:
- Structure: HNO₂ has one hydroxyl group (–OH) and one nitrogen atom.
- Replaceable H⁺: It can donate 1 H⁺.
- **Classification**: Monobasic.

Now, let's summarize the classifications:
- Monobasic acids: H₃PO₂, H₃BO₃, HNO₂
- Dibasic acids: H₃PO₃, H₂CO₃, H₂SO₄, H₂S₂O₈, H₂CrO₄

**Total Monobasic Acids**: 3 (H₃PO₂, H₃BO₃, HNO₂)

### Final Answer:
**3 monobasic acids.**