The strongest reducing agent is :

Options

A. `Cl_2 `
B. `Cl^– `
C. `Br^– `
D. `I^– `

Answer

To determine the strongest reducing agent among the given options (Cl2, Cl⁻, Br⁻, or I⁻), we need to analyze the properties of these species in terms of their ability to lose electrons.

### Step-by-Step Solution:

1. **Understanding Reducing Agents**: A reducing agent is a substance that donates electrons in a chemical reaction and gets oxidized in the process. The strength of a reducing agent is determined by its ability to lose electrons easily.

2. **Identifying the Species**: The options provided are:
- Cl2 (chlorine gas)
- Cl⁻ (chloride ion)
- Br⁻ (bromide ion)
- I⁻ (iodide ion)

3. **Analyzing the Anions**: Among the ions (Cl⁻, Br⁻, I⁻), we need to compare their sizes and the ease with which they can lose electrons. The larger the ion, the more easily it can lose an electron due to decreased effective nuclear charge.

4. **Comparing Sizes**:
- Chlorine (Cl) is smaller than bromine (Br), which is smaller than iodine (I).
- Therefore, the sizes of the anions are: I⁻ > Br⁻ > Cl⁻.

5. **Determining Reducing Power**:
- I⁻ is the largest among the three anions, which means it has a lower effective nuclear charge per electron. This allows I⁻ to lose an electron more easily compared to Cl⁻ and Br⁻.
- Cl2 is a molecular species and not an anion, so it cannot act as a reducing agent in this context.

6. **Conclusion**: Since I⁻ is the largest and can lose an electron most easily, it is the strongest reducing agent among the given options.

### Final Answer:
The strongest reducing agent is **I⁻ (iodide ion)**.

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