Beryllium shows different properties from rest of the alkaline earth metals because of its small atomic and ionic size, high electronegativity and high polarising power.But beryllium shows similarities in properties to the second member of the next group i.e. aluminium on account of similar atomic and ionic size and nearly same polarising power
Which amongst the following is soluble in water ?

Options

A. `BeSO_4`
B. `BeO`
C. `Be(OH)_2`
D. `BeCl_2`

Explanation

To solve the question regarding the solubility of beryllium compounds in water, we will analyze the solubility of the given options based on the properties of beryllium and its compounds.

### Step-by-Step Solution:

1. **Understanding Beryllium's Properties**:
- Beryllium (Be) is the first element in Group 2 (alkaline earth metals).
- It has a small atomic and ionic size, high electronegativity, and high polarizing power.
- These properties lead to unique behavior compared to other alkaline earth metals.

2. **Analyzing Beryllium Sulfate (BeSO4)**:
- Beryllium sulfate is known to be soluble in water.
- The solubility can be attributed to the balance between lattice enthalpy and hydration enthalpy.
- Lattice enthalpy remains relatively constant for sulfates, while hydration enthalpy decreases down the group.
- Due to its small size, Be2+ has a high hydration enthalpy, making BeSO4 soluble.

3. **Analyzing Beryllium Oxide (BeO)**:
- Beryllium oxide is primarily covalent due to the small size of Be.
- It does not readily dissolve in water because it does not form ionic bonds effectively.
- Therefore, BeO is insoluble in water.

4. **Analyzing Beryllium Hydroxide (Be(OH)2)**:
- Beryllium hydroxide is amphoteric; it can react with acids and bases.
- However, it is generally considered insoluble in water.
- Its solubility increases with the increase in size of the alkaline earth metal hydroxides down the group, but Be(OH)2 remains less soluble compared to its heavier counterparts.

5. **Conclusion**:
- Among the compounds discussed, **Beryllium Sulfate (BeSO4)** is the only compound that is soluble in water.

### Final Answer:
**Beryllium Sulfate (BeSO4) is soluble in water.**

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