Among the halides of the elements of group 13 the one which is most acidic is

Options

A. `BF_(3)`
B. `AlCl_(3)`
C. `BCl_(3)`
D. `BBr_(3)`

Explanation

To determine which halide among the elements of group 13 is the most acidic, we need to analyze the halides of boron (B), aluminum (Al), gallium (Ga), indium (In), and thallium (Tl). The halides in question are BBr3, AlBr3, GaBr3, InBr3, and TlBr3.

### Step-by-Step Solution:

1. **Identify the Halides**: The halides of group 13 elements include:
- Boron: BBr3
- Aluminum: AlBr3
- Gallium: GaBr3
- Indium: InBr3
- Thallium: TlBr3

2. **Understand Acidity in Halides**: The acidity of these halides can be related to their ability to accept electrons (Lewis acidity). A compound that can accept electrons more readily is considered more acidic.

3. **Consider the Size of the Central Atom**:
- Boron is the smallest atom in group 13, and it has a high charge density. This allows it to accept electrons more easily compared to larger atoms like aluminum, gallium, indium, and thallium.
- As we move down the group, the size of the central atom increases, which generally decreases the acidity.

4. **Analyze the Halides**:
- BBr3 is a strong Lewis acid because boron can accept a pair of electrons due to its small size and high charge density.
- AlBr3 is also a Lewis acid but is less acidic than BBr3.
- GaBr3, InBr3, and TlBr3 are progressively less acidic than AlBr3 due to the increasing size of the central atoms.

5. **Conclusion**: Based on the above analysis, BBr3 is the most acidic halide among the group 13 elements because it can accept electrons more readily than the other halides.

### Final Answer:
The most acidic halide among the elements of group 13 is **BBr3**.

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