The trihalides of group `13` are hydrolysed by water and they fume in moist air due to the

Options

A. Formation of hydrogen halide
B. Formation of haloboric acid
C. Formation of halogen gases
D. None of the above

Explanation

To answer the question regarding why the trihalides of group 13 fume in moist air and are hydrolyzed by water, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Group 13 Trihalides**:
- The trihalides of group 13 elements include compounds like Aluminum Chloride (AlCl₃), Gallium Chloride (GaCl₃), etc.

2. **Understand Hydrolysis**:
- Hydrolysis is a chemical reaction involving water, where a compound reacts with water to form new products. In the case of aluminum chloride, it reacts with water.

3. **Reaction of Aluminum Chloride with Water**:
- When aluminum chloride (AlCl₃) comes into contact with water, it undergoes hydrolysis:
\[ AlCl_3 + 3H_2O \rightarrow Al(OH)_3 + 3HCl \]
- In this reaction, aluminum hydroxide (Al(OH)₃) is formed as a white precipitate, and hydrochloric acid (HCl) is released.

4. **Formation of Fumes**:
- The hydrochloric acid (HCl) produced is a gas at room temperature and can easily evaporate, especially in moist air. This results in the formation of fumes.
- The presence of moisture in the air facilitates the hydrolysis reaction and enhances the fuming effect.

5. **Conclusion**:
- Therefore, the trihalides of group 13 fume in moist air due to the release of hydrogen halides (like HCl) upon hydrolysis when they react with water.

### Final Answer:
The trihalides of group 13 are hydrolyzed by water and fume in moist air due to the formation of hydrogen halides (like HCl) during the hydrolysis reaction.

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