Oxidation state of `+1` for phophorous is found in

Options

A. `H_(3)PO_(3)`
B. `H_(3)PO_(4)`
C. `H_(3)PO_(2)`
D. `H_(4)P_(2)O_(7)`

Answer

To determine the oxidation state of phosphorus in the given compounds, we will use the oxidation number method. Let's analyze each compound step by step.

### Step 1: Analyze H3PO3
1. Let the oxidation state of phosphorus (P) be \( X \).
2. The contribution from hydrogen (H) is \( +1 \times 3 = +3 \).
3. The contribution from oxygen (O) is \( -2 \times 3 = -6 \).
4. Setting up the equation:
\[ +3 + X - 6 = 0 \]
5. Simplifying gives:
\[ X - 3 = 0 \implies X = +3 \]

### Step 2: Analyze H3PO4
1. Let the oxidation state of phosphorus (P) be \( X \).
2. The contribution from hydrogen (H) is \( +1 \times 3 = +3 \).
3. The contribution from oxygen (O) is \( -2 \times 4 = -8 \).
4. Setting up the equation:
\[ +3 + X - 8 = 0 \]
5. Simplifying gives:
\[ X - 5 = 0 \implies X = +5 \]

### Step 3: Analyze H3PO2
1. Let the oxidation state of phosphorus (P) be \( X \).
2. The contribution from hydrogen (H) is \( +1 \times 3 = +3 \).
3. The contribution from oxygen (O) is \( -2 \times 2 = -4 \).
4. Setting up the equation:
\[ +3 + X - 4 = 0 \]
5. Simplifying gives:
\[ X - 1 = 0 \implies X = +1 \]

### Step 4: Analyze H4P2O7
1. Let the oxidation state of phosphorus (P) be \( X \).
2. There are 2 phosphorus atoms, so their contribution is \( 2X \).
3. The contribution from hydrogen (H) is \( +1 \times 4 = +4 \).
4. The contribution from oxygen (O) is \( -2 \times 7 = -14 \).
5. Setting up the equation:
\[ +4 + 2X - 14 = 0 \]
6. Simplifying gives:
\[ 2X - 10 = 0 \implies 2X = +10 \implies X = +5 \]

### Summary of Oxidation States:
- **H3PO3**: +3
- **H3PO4**: +5
- **H3PO2**: +1
- **H4P2O7**: +5

### Conclusion:
The oxidation state of +1 for phosphorus is found in **H3PO2**.

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