Select the correct answer from the list in bracket :
The anion discharged at the anode with most difficulty.

Answer

To determine which anion is discharged at the anode with the most difficulty, we need to analyze the given options based on their position in the electrochemical series and their tendency to get discharged.

### Step-by-Step Solution:

1. **Understand the Question**: We need to identify which anion from the given options is discharged at the anode with the most difficulty.

2. **List the Given Anions**: The options provided are:
- SO₄²⁻ (Sulfate)
- NO₃⁻ (Nitrate)
- OH⁻ (Hydroxide)

3. **Review the Electrochemical Series**: The electrochemical series ranks ions based on their standard electrode potentials. Anions that are higher in the series are less likely to be discharged because they are more stable in their ionic form.

4. **Analyze Each Anion**:
- **SO₄²⁻ (Sulfate)**: This ion is relatively stable and is positioned higher in the electrochemical series, making it less likely to be discharged.
- **NO₃⁻ (Nitrate)**: This ion is also stable but is lower than sulfate in the series, indicating it can be discharged more easily than sulfate.
- **OH⁻ (Hydroxide)**: Hydroxide ions are generally discharged more readily compared to sulfate ions.

5. **Conclusion**: Among the given anions, SO₄²⁻ is the one that is discharged at the anode with the most difficulty due to its higher stability and position in the electrochemical series.

### Final Answer:
The anion discharged at the anode with the most difficulty is **SO₄²⁻ (Sulfate)**.

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