Phosphorous has the oxidation state of +1 in:

Options

A. (a)Orthophosphoric acid
B. (b)Phosphorous acid
C. (C)Hypophosphoric acid
D. (d)Metaphosphoric acid

Answer

To determine the oxidation state of phosphorus in various compounds, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Compound**: We need to analyze the oxidation state of phosphorus in the given compounds: orthophosphoric acid (H₃PO₄), phosphorus acid (H₃PO₃), hypophosphorous acid (H₃PO₂), and metaphosphoric acid (HPO₃).

2. **Orthophosphoric Acid (H₃PO₄)**:
- Let the oxidation state of phosphorus be \( x \).
- The oxidation state of hydrogen (H) is +1, and there are 3 hydrogen atoms: \( 3 \times (+1) = +3 \).
- The oxidation state of oxygen (O) is -2, and there are 4 oxygen atoms: \( 4 \times (-2) = -8 \).
- The overall charge of the compound is neutral (0), so we set up the equation:
\[ +3 + x - 8 = 0 \]
- Simplifying gives:
\[ x - 5 = 0 \implies x = +5 \]
- Therefore, the oxidation state of phosphorus in orthophosphoric acid is +5.

3. **Phosphorus Acid (H₃PO₃)**:
- Let the oxidation state of phosphorus be \( x \).
- The oxidation state of hydrogen is +1, and there are 3 hydrogen atoms: \( 3 \times (+1) = +3 \).
- The oxidation state of oxygen is -2, and there are 3 oxygen atoms: \( 3 \times (-2) = -6 \).
- Setting up the equation:
\[ +3 + x - 6 = 0 \]
- Simplifying gives:
\[ x - 3 = 0 \implies x = +3 \]
- Therefore, the oxidation state of phosphorus in phosphorus acid is +3.

4. **Hypophosphorous Acid (H₃PO₂)**:
- Let the oxidation state of phosphorus be \( x \).
- The oxidation state of hydrogen is +1, and there are 3 hydrogen atoms: \( 3 \times (+1) = +3 \).
- The oxidation state of oxygen is -2, and there are 2 oxygen atoms: \( 2 \times (-2) = -4 \).
- Setting up the equation:
\[ +3 + x - 4 = 0 \]
- Simplifying gives:
\[ x - 1 = 0 \implies x = +1 \]
- Therefore, the oxidation state of phosphorus in hypophosphorous acid is +1.

5. **Metaphosphoric Acid (HPO₃)**:
- Let the oxidation state of phosphorus be \( x \).
- The oxidation state of hydrogen is +1, and there is 1 hydrogen atom: \( 1 \times (+1) = +1 \).
- The oxidation state of oxygen is -2, and there are 3 oxygen atoms: \( 3 \times (-2) = -6 \).
- Setting up the equation:
\[ +1 + x - 6 = 0 \]
- Simplifying gives:
\[ x - 5 = 0 \implies x = +5 \]
- Therefore, the oxidation state of phosphorus in metaphosphoric acid is +5.

### Conclusion:
The oxidation state of phosphorus is +1 in **hypophosphorous acid (H₃PO₂)**.

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