Which one of the following acids would you expect to be the strongest?

Options

A. `I-CH_(2)COOH`
B. `Cl-CH_(2)COOH`
C. `Br-CH_(2)COOH`
D. `F-CH_(2)COOH`

Explanation

To determine which of the given acids is the strongest, we need to analyze the stability of the anions formed when these acids donate a proton (H+). The stronger the acid, the more stable the anion it forms.

### Step-by-Step Solution:

1. **Identify the Acids**: Let's assume the acids in question are represented as follows:
- Acid A: RCOOH (with a substituent that has a -I effect)
- Acid B: RCOOH (with a different substituent that has a -I effect)
- Acid C: RCOOH (with another substituent that has a -I effect)
- Acid D: RCOOH (with a substituent that has a strong -I effect)

2. **Understand the -I Effect**: The -I (inductive) effect refers to the electron-withdrawing effect of substituents. The more electronegative the substituent, the stronger its -I effect, which stabilizes the negative charge on the anion formed after the acid donates a proton.

3. **Analyze the Substituents**:
- Fluorine (F) is the most electronegative element, followed by chlorine (Cl), bromine (Br), and iodine (I).
- Therefore, the order of -I effect strength is: F > Cl > Br > I.

4. **Determine Anion Stability**:
- When each acid donates a proton (H+), it forms an anion. The stability of this anion is influenced by the substituent's -I effect.
- The more stable the anion, the stronger the acid.

5. **Compare the Acids**:
- If Acid D has a fluorine substituent, it will create a more stable anion compared to the others with Cl, Br, or I substituents.
- Thus, Acid D is expected to be the strongest acid because it forms the most stable anion.

6. **Conclusion**: Based on the analysis, the acid with the substituent that has the strongest -I effect (in this case, fluorine) will be the strongest acid. Therefore, Acid D is the strongest acid among the options provided.

### Final Answer:
**The strongest acid is Acid D.**