`MnO_(4)^(-)+8H^(+)+5e to Mn^(2+)+4H_(2)O" "E^(0)=+1.51V`
`Fe^(3+)+e to Fe^(2+)" "E^(0)=+0.77V`
`Cl_(2)+2e to 2Cl^(-) " "E^(0)=+1.36V`
`Ce^(4+)+e to Ce^(3+) " "E^(0)=1.76`
Choose the incorrect statement among the following:

Options

A. `MnO_(4)^(+)` is a sufficlently strong oxidant In acidic solution (pH =0) to oxidize `Fe^(2+)` ion.
B. `Fe^(2+)` ion cannot be titrated against standard `KMnO_4` solution if the, medium is made acidic (pH =0) by adding HCl.
C. `MnO_(4)^(-),` ion cannot oxidize Cet in acidic medium (pH =0)
D. `Fe^(2+)` cannot be titrated against standard `KMnO_4` solution in acid medium (pH =0) in presence of `Ce^(3+)` ion.

Answer

To solve the problem, we need to analyze the given half-reactions and their standard reduction potentials (E° values) to determine which statement is incorrect. Let's break down the steps:

### Step 1: List the half-reactions and their E° values
1. \( \text{MnO}_4^{-} + 8\text{H}^{+} + 5e^{-} \rightarrow \text{Mn}^{2+} + 4\text{H}_2\text{O} \) (E° = +1.51 V)
2. \( \text{Fe}^{3+} + e^{-} \rightarrow \text{Fe}^{2+} \) (E° = +0.77 V)
3. \( \text{Cl}_2 + 2e^{-} \rightarrow 2\text{Cl}^{-} \) (E° = +1.36 V)
4. \( \text{Ce}^{4+} + e^{-} \rightarrow \text{Ce}^{3+} \) (E° = +1.76 V)

### Step 2: Understand the oxidizing and reducing power
- The higher the E° value, the stronger the oxidizing agent.
- The lower the E° value, the stronger the reducing agent.

### Step 3: Analyze each statement
1. **Statement 1**: "MnO4⁻ is a sufficiently strong oxidant in acidic medium to oxidize Fe²⁺ ion."
- E° for MnO4⁻ = +1.51 V, E° for Fe³⁺/Fe²⁺ = +0.77 V.
- Since +1.51 V > +0.77 V, MnO4⁻ can oxidize Fe²⁺. **This statement is correct.**

2. **Statement 2**: "Fe²⁺ ion cannot be titrated against KMnO₄ solution if the medium is made acidic by adding HCl."
- HCl produces Cl⁻ ions, which can also be oxidized by MnO4⁻.
- The presence of Cl⁻ would interfere with the titration of Fe²⁺. **This statement is correct.**

3. **Statement 3**: "MnO4⁻ cannot oxidize Ce³⁺ in acidic medium."
- E° for Ce⁴⁺/Ce³⁺ = +1.76 V, which is greater than that for MnO4⁻.
- Since +1.76 V > +1.51 V, MnO4⁻ cannot oxidize Ce³⁺. **This statement is correct.**

4. **Statement 4**: "Fe²⁺ cannot be titrated against KMnO₄ in acidic solution in the presence of Ce³⁺ ion."
- This statement is incorrect because KMnO₄ can still oxidize Fe²⁺ to Fe³⁺, and the presence of Ce³⁺ does not hinder this reaction as Ce³⁺ is not oxidized by KMnO₄ in this scenario. **This statement is incorrect.**

### Conclusion
The incorrect statement is **Statement 4**.