1 mole of how many of the following acids neutralize exactly one mol of NaOH, under required favourable conditions ? HCl, `HNO_(3), H_(2)SO_(4),H_(2)SO_(3),H_(3)PO_(4),H_(3)PO_(2),H_(4)P_(2)O_(5),H_(3)BO_(3)`

Options

A. 4
B. 7
C. 8
D. 9

Explanation

To determine how many of the given acids can neutralize exactly one mole of NaOH, we need to identify which of these acids are monoprotic. A monoprotic acid is one that can donate only one proton (H⁺ ion) per molecule when it reacts with a base.

Let's analyze each acid step by step:

1. **HCl (Hydrochloric Acid)**:
- HCl is a strong acid that dissociates completely in water to give one H⁺ ion.
- **Conclusion**: Monoprotic (1 mole of H⁺).

2. **HNO₃ (Nitric Acid)**:
- HNO₃ also dissociates completely in water to produce one H⁺ ion.
- **Conclusion**: Monoprotic (1 mole of H⁺).

3. **H₂SO₄ (Sulfuric Acid)**:
- H₂SO₄ is a diprotic acid, meaning it can donate two H⁺ ions (one from the first dissociation and one from the second).
- **Conclusion**: Not monoprotic (2 moles of H⁺).

4. **H₂SO₃ (Sulfurous Acid)**:
- H₂SO₃ is also a diprotic acid, capable of donating two H⁺ ions.
- **Conclusion**: Not monoprotic (2 moles of H⁺).

5. **H₃PO₄ (Phosphoric Acid)**:
- H₃PO₄ is a triprotic acid, meaning it can donate three H⁺ ions.
- **Conclusion**: Not monoprotic (3 moles of H⁺).

6. **H₃PO₂ (Hypophosphorous Acid)**:
- H₃PO₂ can donate only one H⁺ ion.
- **Conclusion**: Monoprotic (1 mole of H⁺).

7. **H₄P₂O₅ (Pyrophosphoric Acid)**:
- H₄P₂O₅ has two acidic protons that can be released.
- **Conclusion**: Not monoprotic (2 moles of H⁺).

8. **H₃BO₃ (Boric Acid)**:
- H₃BO₃ behaves as a monoprotic acid because it can donate only one H⁺ ion when it reacts with water.
- **Conclusion**: Monoprotic (1 mole of H⁺).

Now, let's summarize the findings:
- Monoprotic acids: HCl, HNO₃, H₃PO₂, H₃BO₃
- Total number of monoprotic acids = 4

**Final Answer**: 4 acids can neutralize exactly one mole of NaOH.