Stannous sulphate `(SnSO_(4))` and potassium permanganate are used as oxidising agents in acidic medium for oxidation of ferrrous ammnium sulphate to ferric sulphate. The ration of number of moles of stannous sulphate required per mole of ferrous ammonium sulphate to the number of moles of `KMnO_(4)` required per mole of ferrous ammonium sulphate, is:

Options

A. 2.5
B. 0.2
C. 0.4
D. 2

Answer

To solve the problem, we need to determine the ratio of the number of moles of stannous sulfate (SnSO₄) required per mole of ferrous ammonium sulfate (Fe(NH₄)₂(SO₄)₂) to the number of moles of potassium permanganate (KMnO₄) required per mole of ferrous ammonium sulfate.

### Step-by-Step Solution:

1. **Identify the Oxidation States and Reactions**:
- Stannous ion (Sn²⁺) is oxidized to stannic ion (Sn⁴⁺).
- Ferrous ion (Fe²⁺) is oxidized to ferric ion (Fe³⁺).
- Potassium permanganate (KMnO₄) in acidic medium reduces from MnO₄⁻ to Mn²⁺.

2. **Determine the n-factor for each species**:
- For Sn²⁺ to Sn⁴⁺: The change in oxidation state is 2 (from +2 to +4), so the n-factor is 2.
- For Fe²⁺ to Fe³⁺: The change in oxidation state is 1 (from +2 to +3), so the n-factor is 1.
- For KMnO₄ to Mn²⁺: The change in oxidation state is 7 (from +7 to +2), so the n-factor is 5.

3. **Set up the equations based on equivalents**:
- Let the number of moles of Sn²⁺ required be 'a' and the number of moles of Fe²⁺ be 'b'.
- The number of equivalents of Sn²⁺ must equal the number of equivalents of Fe²⁺:
\[ 2a = 1b \quad \text{(Equation 1)} \]
- Let the number of moles of KMnO₄ required be 'c'.
- The number of equivalents of KMnO₄ must equal the number of equivalents of Fe²⁺:
\[ 5c = 1b \quad \text{(Equation 2)} \]

4. **Express 'b' in terms of 'a' and 'c'**:
- From Equation 1:
\[ b = 2a \]
- From Equation 2:
\[ b = 5c \]

5. **Set the two expressions for 'b' equal to each other**:
\[ 2a = 5c \]

6. **Solve for the ratio \( \frac{a}{c} \)**:
\[ \frac{a}{c} = \frac{5}{2} \]

7. **Final Ratio**:
The ratio of the number of moles of stannous sulfate required per mole of ferrous ammonium sulfate to the number of moles of KMnO₄ required per mole of ferrous ammonium sulfate is:
\[ \frac{a}{c} = 2.5 \]

### Conclusion:
The final answer is 2.5.

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