Which of the following statements is incorrect ?

Options

A. Dissolution of group IA hydroxide is endothermic
B. Group IA hydroxide are hygroscopic
C. Group IA hydroxides form ionic crystals
D. Aqueous solution of group IA hydroxides are strongly basic

Answer

To determine which statement is incorrect regarding the properties of Group 1A hydroxides (alkali metal hydroxides), let's analyze each statement step by step.

### Step-by-Step Solution:

1. **Statement Analysis**:
- **Statement 1**: "Dissolution of group 1A hydroxide is endothermic."
- **Explanation**: The dissolution of alkali metal hydroxides (like NaOH, KOH) in water is an exothermic process, meaning it releases heat. Therefore, this statement is incorrect.

2. **Statement 2**: "Group 1A hydroxides are hygroscopic."
- **Explanation**: Hygroscopic substances absorb moisture from the air. Alkali metal hydroxides, such as NaOH and KOH, are indeed hygroscopic. This statement is correct.

3. **Statement 3**: "Group 1A hydroxides form ionic crystals."
- **Explanation**: Alkali metal hydroxides consist of ions (e.g., Na⁺ and OH⁻) and form ionic crystals. This statement is also correct.

### Conclusion:
The incorrect statement among the options provided is **Statement 1**, which claims that the dissolution of Group 1A hydroxides is endothermic. In reality, it is an exothermic process.