Which of the following form maximum `P-H` bonds.

Options

A. `H_3 PO_2`
B. `H_3 PO_4`
C. `H_3 PO_3`
D. `H_4 P_2 O_7`

Answer

To determine which of the given compounds forms the maximum number of P-H bonds, we will analyze each compound's structure step by step.

### Step 1: Analyze H3PO2 (Hypophosphorous Acid)
- **Structure**: The structure of H3PO2 can be drawn as follows:
- Central phosphorus (P) atom.
- One double bond with an oxygen (O) atom.
- One hydroxyl group (OH).
- Two hydrogen (H) atoms bonded directly to phosphorus.

- **P-H Bonds**: In H3PO2, there are **2 P-H bonds**.

### Step 2: Analyze H3PO4 (Phosphoric Acid)
- **Structure**: The structure of H3PO4 is:
- Central phosphorus (P) atom.
- One double bond with an oxygen (O) atom.
- Three hydroxyl groups (OH).

- **P-H Bonds**: In H3PO4, there are **0 P-H bonds**.

### Step 3: Analyze H3PO3 (Phosphorous Acid)
- **Structure**: The structure of H3PO3 is:
- Central phosphorus (P) atom.
- One double bond with an oxygen (O) atom.
- Two hydroxyl groups (OH).
- One hydrogen (H) atom bonded directly to phosphorus.

- **P-H Bonds**: In H3PO3, there is **1 P-H bond**.

### Step 4: Analyze H4P2O7 (Pyrophosphoric Acid)
- **Structure**: The structure of H4P2O7 is:
- Two phosphorus (P) atoms.
- Each phosphorus is double bonded to an oxygen (O).
- There are two hydroxyl groups (OH).

- **P-H Bonds**: In H4P2O7, there are **0 P-H bonds**.

### Conclusion
After analyzing all the compounds:
- H3PO2 has **2 P-H bonds**.
- H3PO4 has **0 P-H bonds**.
- H3PO3 has **1 P-H bond**.
- H4P2O7 has **0 P-H bonds**.

Thus, the compound that forms the maximum number of P-H bonds is **H3PO2** (Hypophosphorous Acid), which has **2 P-H bonds**.

### Final Answer
The answer is **H3PO2**.

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