Assuming complete ionization, same moles of which of the following compounds will require the least amount of acidified `KMnO_(4)` for complete oxidation ?

Options

A. `FeSO_(4)`
B. `FeSO_(3)`
C. `FeC_(2)O_(4)`
D. `Fe(NO_(2))_(2)`

Explanation

To solve the question of which compound will require the least amount of acidified KMnO4 for complete oxidation, we need to analyze the oxidation states of the anions present in the given compounds.

### Step-by-Step Solution:

1. **Identify the Compounds**:
We need to consider the compounds that are being compared. The anions mentioned are SO4^2-, SO3^2-, C2O4^2-, and NO2^-.

2. **Determine the Oxidation States**:
- **SO4^2- (Sulfate)**: Sulfur is in the +6 oxidation state, which is its highest oxidation state. Therefore, it cannot be oxidized further.
- **SO3^2- (Sulfite)**: Sulfur is in the +4 oxidation state. It can be oxidized to SO4^2- (sulfate), which means it will require KMnO4 for oxidation.
- **C2O4^2- (Oxalate)**: Carbon is in the +3 oxidation state in oxalate and can be oxidized to CO2 (where carbon is in the +4 oxidation state). Thus, it will also require KMnO4 for oxidation.
- **NO2^- (Nitrite)**: Nitrogen is in the +3 oxidation state and can be oxidized to NO3^- (nitrate), which means KMnO4 will be needed for this oxidation as well.

3. **Compare the Oxidation Potentials**:
- Among these, SO4^2- does not undergo oxidation because it is already in the highest oxidation state.
- SO3^2-, C2O4^2-, and NO2^- can all be oxidized, but since SO4^2- does not require any KMnO4 for oxidation, it will require the least amount of KMnO4.

4. **Conclusion**:
Therefore, the compound that will require the least amount of acidified KMnO4 for complete oxidation is **SO4^2- (Sulfate)**, as it does not undergo any oxidation.

### Final Answer:
**SO4^2- (Sulfate)** will require the least amount of acidified KMnO4 for complete oxidation.