Which of the following acids is monobasic?

Options

A. Hypophosphorus acid `(H_(3)PO_(2))`
B. Orthophosphoric acid `(H_(3)PO_(4))`
C. Pyrophorusphoric acid `(H_(4)P_(2)O_(7))`
D. Hypohosphoric acid `(H_(4)P_(2)O_(6))`

Explanation

To determine which of the following acids is monobasic, we first need to understand the definition of a monobasic acid. A monobasic acid is one that can donate only one hydrogen ion (H⁺) per molecule when dissolved in water.

### Step-by-Step Solution:

1. **Identify the Acids**: We need to look at the given acids to determine their structures and how many H⁺ ions they can donate. The acids mentioned in the video transcript are:
- Hypophosphorous acid (H₃PO₂)
- Phosphoric acid (H₃PO₄)
- Pyrophosphoric acid (H₄P₂O₇)

2. **Analyze Hypophosphorous Acid (H₃PO₂)**:
- Structure: H₃PO₂ can be represented as H-O-P=O with one H attached to the oxygen.
- It has one hydroxyl group (-OH) that can donate one H⁺ ion.
- Conclusion: Hypophosphorous acid is monobasic.

3. **Analyze Phosphoric Acid (H₃PO₄)**:
- Structure: H₃PO₄ has three hydroxyl groups (-OH).
- It can donate three H⁺ ions (one from each hydroxyl group).
- Conclusion: Phosphoric acid is not monobasic; it is tribasic.

4. **Analyze Pyrophosphoric Acid (H₄P₂O₇)**:
- Structure: H₄P₂O₇ has multiple hydroxyl groups.
- It can also donate more than one H⁺ ion.
- Conclusion: Pyrophosphoric acid is not monobasic; it is tetrabasic.

5. **Final Conclusion**: Among the acids analyzed, only hypophosphorous acid (H₃PO₂) is monobasic because it can donate only one H⁺ ion.

### Answer:
The monobasic acid among the given options is **Hypophosphorous acid (H₃PO₂)**.