The strongest Bronsted base in the following anion is:

Options

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

Answer

To determine the strongest Bronsted base among the given anions, we need to follow these steps:

### Step 1: Understand Bronsted-Lowry Theory
According to the Bronsted-Lowry theory, a Bronsted base is a species that can accept a proton (H⁺). When a base accepts a proton, it forms its conjugate acid. Conversely, an acid is a species that can donate a proton, forming its conjugate base.

**Hint:** Remember that the strength of a base is inversely related to the strength of its conjugate acid.

### Step 2: Identify the Anions and Their Conjugate Acids
We need to identify the anions given in the question and their corresponding conjugate acids. For example:
- CN⁻ (cyanide ion) → HCN (hydrocyanic acid)
- Cl⁻ (chloride ion) → HCl (hydrochloric acid)
- I⁻ (iodide ion) → HI (hydroiodic acid)
- Br⁻ (bromide ion) → HBr (hydrobromic acid)

**Hint:** Write down the anions and their conjugate acids to visualize the relationship.

### Step 3: Determine the Strength of the Conjugate Acids
Next, we need to evaluate the strength of the conjugate acids formed:
- HCN: Weak acid
- HCl: Strong acid
- HI: Strong acid
- HBr: Strong acid

Among these, HCl is the weakest acid.

**Hint:** Recall that strong acids have weak conjugate bases, while weak acids have strong conjugate bases.

### Step 4: Identify the Strongest Bronsted Base
Since HCl is the weakest acid among the conjugate acids listed, its conjugate base (Cl⁻) will be the strongest Bronsted base. However, we are looking for the strongest Bronsted base among the anions provided.

Since CN⁻ is the conjugate base of the weak acid HCN, it will be a stronger base than Cl⁻, I⁻, and Br⁻.

**Hint:** The weaker the acid, the stronger its conjugate base.

### Conclusion
Thus, among the given anions, CN⁻ (cyanide ion) is the strongest Bronsted base.

**Final Answer:** The strongest Bronsted base is CN⁻.