In which of the following comp. H atom is directly linked with phosphorus

Options

A. `H_3PO_2`
B. `H_3PO_3`
C. `H_3PO_4`
D. `H_4P_2O_7`

Answer

To determine in which of the given compounds the hydrogen atom is directly linked with phosphorus, we will analyze the structures of each compound step by step.

### Step 1: Analyze H3PO2 (Hypophosphorous Acid)
1. **Structure**: The structure of H3PO2 can be represented as:
- P is the central atom.
- There is a double bond between P and O (P=O).
- There is one OH group (which contains one H).
- There are two additional H atoms directly bonded to P.

**Conclusion**: In H3PO2, there are two direct linkages between hydrogen and phosphorus.

### Step 2: Analyze H3PO3 (Phosphorus Acid)
1. **Structure**: The structure of H3PO3 can be represented as:
- P is the central atom.
- There is a double bond between P and O (P=O).
- There are two OH groups (each containing one H).
- There is one additional H atom directly bonded to P.

**Conclusion**: In H3PO3, there is one direct linkage between hydrogen and phosphorus.

### Step 3: Analyze H3PO4 (Orthophosphoric Acid)
1. **Structure**: The structure of H3PO4 can be represented as:
- P is the central atom.
- There is a double bond between P and O (P=O).
- There are three OH groups (each containing one H).

**Conclusion**: In H3PO4, there are no direct linkages between hydrogen and phosphorus; all hydrogens are linked through oxygen.

### Step 4: Analyze H4P2O7 (Pyrophosphoric Acid)
1. **Structure**: The structure of H4P2O7 can be represented as:
- There are two phosphorus atoms.
- Each phosphorus is connected to oxygen atoms.
- The hydrogens are linked through OH groups.

**Conclusion**: In H4P2O7, there are no direct linkages between hydrogen and phosphorus; the hydrogens are linked through oxygen.

### Final Conclusion
The compounds in which hydrogen is directly linked to phosphorus are **H3PO2** and **H3PO3**.