Phosphorus has the oxidation state of +3 in

Options

A. ortho phosphoric acid
B. phosphorus acid
C. meta phosphoric acid
D. pyro phosphoric acid.

Answer

To determine the oxidation state of phosphorus in the given compounds, we will analyze each compound step by step.

### Step 1: Identify the Compounds
We have four compounds to analyze:
1. Orthophosphoric acid (H₃PO₄)
2. Phosphorous acid (H₃PO₃)
3. Metaphosphoric acid (HPO₃)
4. Pyrophosphoric acid (H₄P₂O₇)

### Step 2: Assign Oxidation States
We will use the known oxidation states of hydrogen (+1) and oxygen (-2) to find the oxidation state of phosphorus (P) in each compound.

#### a. Orthophosphoric Acid (H₃PO₄)
- Formula: H₃PO₄
- Oxidation state equation:
\[ 3(+1) + x + 4(-2) = 0 \]
\[ 3 + x - 8 = 0 \]
\[ x - 5 = 0 \implies x = +5 \]
- Oxidation state of phosphorus in H₃PO₄ is +5.

#### b. Phosphorous Acid (H₃PO₃)
- Formula: H₃PO₃
- Oxidation state equation:
\[ 3(+1) + x + 3(-2) = 0 \]
\[ 3 + x - 6 = 0 \]
\[ x - 3 = 0 \implies x = +3 \]
- Oxidation state of phosphorus in H₃PO₃ is +3.

#### c. Metaphosphoric Acid (HPO₃)
- Formula: HPO₃
- Oxidation state equation:
\[ 1(+1) + x + 3(-2) = 0 \]
\[ 1 + x - 6 = 0 \]
\[ x - 5 = 0 \implies x = +5 \]
- Oxidation state of phosphorus in HPO₃ is +5.

#### d. Pyrophosphoric Acid (H₄P₂O₇)
- Formula: H₄P₂O₇
- Oxidation state equation:
\[ 4(+1) + 2x + 7(-2) = 0 \]
\[ 4 + 2x - 14 = 0 \]
\[ 2x - 10 = 0 \implies 2x = 10 \implies x = +5 \]
- Oxidation state of phosphorus in H₄P₂O₇ is +5.

### Step 3: Conclusion
Among the four compounds, phosphorus has an oxidation state of +3 only in **phosphorous acid (H₃PO₃)**.

### Final Answer
Phosphorus has the oxidation state of +3 in **phosphorous acid (H₃PO₃)**.

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