Which of the following anions is most easily polarized ?

Options

A. `CI^(-)`
B. `Se^(2-)`
C. `Br^(-)`
D. `Te^(2-)`.

Answer

To determine which of the given anions is most easily polarized, we need to analyze the polarizability of each anion based on their size and charge. The options provided are Cl⁻, Se²⁻, Br⁻, and Te²⁻.

### Step-by-Step Solution:

1. **Understand Polarizability**:
- Polarizability refers to the ability of an anion to become polarized, which means how easily its electron cloud can be distorted by an external electric field or by the presence of a cation.

2. **Factors Affecting Polarizability**:
- The polarizability of an anion increases with:
- **Size**: Larger anions have more electrons that are farther from the nucleus, making them easier to polarize.
- **Charge**: Anions with higher negative charges are more polarizable because the increased electron-electron repulsion makes the electron cloud more easily distorted.

3. **Analyze the Given Anions**:
- **Cl⁻**: Has a single negative charge and is relatively small in size.
- **Br⁻**: Also has a single negative charge, but is larger than Cl⁻.
- **Se²⁻**: Has a double negative charge and is larger than both Cl⁻ and Br⁻.
- **Te²⁻**: Has a double negative charge and is larger than Se²⁻.

4. **Compare the Anions**:
- Cl⁻ has the least polarizability due to its smaller size and single charge.
- Br⁻ is more polarizable than Cl⁻ because it is larger, but still has a single charge.
- Se²⁻ is more polarizable than both Cl⁻ and Br⁻ due to its larger size and double charge.
- Te²⁻ is the largest anion among the options and also has a double charge, making it the most polarizable.

5. **Conclusion**:
- Among the given anions, **Te²⁻** is the most easily polarized due to its larger size and higher negative charge.

### Final Answer:
**Te²⁻ is the most easily polarized anion.**

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