`H_(3)PO_(2)+AgNO_(2) to Ag darr+H_(3)PO_(4)+NO`

Options

A. For disproportionation reaction.
B. For comproportionation reaction.
C. For either intermolecular redox reaction or displacement reaction
D. For either thermal combination redox reaction or thermal decomposition redox reaction.

Answer

To determine the type of reaction occurring in the equation \( H_3PO_2 + AgNO_2 \rightarrow Ag + H_3PO_4 + NO \), we will analyze the oxidation states of the elements involved and identify the changes that occur during the reaction.

### Step-by-Step Solution:

1. **Identify Reactants and Products**:
- Reactants: \( H_3PO_2 \) (phosphorous acid) and \( AgNO_2 \) (silver nitrite).
- Products: \( Ag \) (silver), \( H_3PO_4 \) (phosphoric acid), and \( NO \) (nitric oxide).

2. **Assign Oxidation States**:
- For \( H_3PO_2 \):
- Hydrogen (H) = +1 (3 H atoms contribute +3)
- Oxygen (O) = -2 (2 O atoms contribute -4)
- Let the oxidation state of phosphorus (P) = \( x \).
- Equation: \( 3(+1) + x + 2(-2) = 0 \) → \( 3 + x - 4 = 0 \) → \( x = +1 \).
- For \( AgNO_2 \):
- Silver (Ag) = +1
- Nitrogen (N) = +3 (let's verify)
- Oxygen (O) = -2 (2 O atoms contribute -4)
- Equation: \( +1 + x + 2(-2) = 0 \) → \( 1 + x - 4 = 0 \) → \( x = +3 \).
- For \( H_3PO_4 \):
- Hydrogen (H) = +1 (3 H atoms contribute +3)
- Oxygen (O) = -2 (4 O atoms contribute -8)
- Let the oxidation state of phosphorus (P) = \( y \).
- Equation: \( 3(+1) + y + 4(-2) = 0 \) → \( 3 + y - 8 = 0 \) → \( y = +5 \).
- For \( NO \):
- Nitrogen (N) = +2 (let's verify)
- Oxygen (O) = -2
- Equation: \( x + (-2) = 0 \) → \( x = +2 \).

3. **Determine Changes in Oxidation States**:
- Phosphorus changes from +1 (in \( H_3PO_2 \)) to +5 (in \( H_3PO_4 \)) → **Oxidation** (loss of electrons).
- Silver changes from +1 (in \( AgNO_2 \)) to 0 (elemental Ag) → **Reduction** (gain of electrons).
- Nitrogen changes from +3 (in \( AgNO_2 \)) to +2 (in \( NO \)) → **Reduction** (gain of electrons).

4. **Identify the Type of Reaction**:
- Since we have one element (P) undergoing oxidation and two elements (Ag and N) undergoing reduction, this reaction does not fit the criteria for disproportionation or comproportionation.
- The reaction involves multiple species and their oxidation states changing, indicating it is an **intermolecular redox reaction**.

5. **Conclusion**:
- The type of reaction is an **intermolecular redox reaction**.