Which of the following is the weakest acid?

Options

A. (1) HF
B. (2) HCI
C. (3) HBr
D. (4) HI

Explanation

To determine which of the following is the weakest acid among hydrogen halides (HF, HCl, HBr, HI), we need to analyze their acidic strengths based on their molecular properties.

### Step-by-Step Solution:

1. **Understanding Acid Strength in Hydrogen Halides**:
The strength of an acid is determined by its ability to donate protons (H⁺ ions). In the case of hydrogen halides, the bond strength and the size of the halogen atoms play a crucial role.

2. **Order of Acid Strength**:
The acidic strength of hydrogen halides follows a specific trend:
- HF (Hydrogen Fluoride)
- HCl (Hydrogen Chloride)
- HBr (Hydrogen Bromide)
- HI (Hydrogen Iodide)

The general order of acidic strength is:
**HF < HCl < HBr < HI**

3. **Identifying the Weakest Acid**:
From the order of acidic strength, we can see that HF is the weakest acid among the hydrogen halides. This is because:
- HF has a strong H-F bond due to the small size and high electronegativity of fluorine, making it less likely to donate a proton.
- In contrast, HI has a weak H-I bond because iodine is larger and less electronegative, allowing it to easily donate a proton.

4. **Conclusion**:
Therefore, the weakest acid among the given options is **HF**.

### Final Answer:
The weakest acid is **HF (Hydrogen Fluoride)**.

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