Which of the following is most basic ?

Options

A. `Cl^(-)`
B. `F^(-)`
C. `I^(-)`
D. `Br^-`

Answer

To determine which of the given anions (Cl⁻, F⁻, I⁻, and Br⁻) is the most basic, we need to analyze their basicity based on their electronegativity and the trend in the periodic table.

### Step-by-Step Solution:

1. **Understanding Basicity**: Basicity refers to the ability of an anion to accept protons (H⁺ ions). The more basic an anion is, the more readily it can accept a proton.

2. **Electronegativity Trend**: In the periodic table, electronegativity decreases as we move down a group. This means that as we go from fluorine (F) to chlorine (Cl), bromine (Br), and iodine (I), the electronegativity decreases.

3. **Basicity and Electronegativity Relationship**: There is an inverse relationship between electronegativity and basicity for anions. As electronegativity decreases, the basic character of the anion increases. Therefore, we can expect the following trend in basicity:
- F⁻ < Cl⁻ < Br⁻ < I⁻

4. **Exception for Fluorine**: However, fluorine is an exception due to its high electronegativity. Even though it is at the top of the group, its high electronegativity means it does not behave like the other halides in terms of basicity.

5. **Revising the Order**: Taking into account the exception for fluorine, we can revise the order of basicity. The correct order of increasing basicity becomes:
- F⁻ < Cl⁻ < Br⁻ < I⁻

6. **Conclusion**: Based on the revised order, the most basic anion among the given options is I⁻ (iodide ion).

### Final Answer:
The most basic anion among Cl⁻, F⁻, I⁻, and Br⁻ is **I⁻**.