Beryllium and aluminimum exhibit many properties which are
similar . But, the two elements differ in

Options

A. Forming covalent halides
B. Forming covalent hydrides
C. Exhibiting maximum covalency in compounds
D. Exhibiting amphoteric nature in their oxides

Explanation

To answer the question, "Beryllium and Aluminium exhibit many properties which are similar. But, the two elements differ in," we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Elements**:
- The elements in question are Beryllium (Be) and Aluminium (Al). Both belong to the group of elements in the periodic table and exhibit some similarities due to their positions.

2. **Understand the Diagonal Relationship**:
- Beryllium and Aluminium show a diagonal relationship in the periodic table, which means they share several chemical and physical properties.

3. **List Similar Properties**:
- Both Beryllium and Aluminium form covalent halides. For example:
- Beryllium forms BeCl2.
- Aluminium forms AlCl3.
- Both form covalent hydrides:
- Beryllium forms BeH2.
- Aluminium forms AlH3.
- Both can exhibit polymeric structures due to their electron deficiency.

4. **Identify the Key Difference**:
- The main difference between Beryllium and Aluminium lies in their maximum covalency:
- Beryllium typically exhibits a maximum covalency of +2.
- Aluminium can exhibit a maximum covalency of +3.
- This difference is attributed to the absence of d-orbitals in Beryllium, while Aluminium has vacant d-orbitals that allow it to expand its valency.

5. **Summarize the Findings**:
- While Beryllium and Aluminium share similarities in forming covalent compounds and exhibiting amphoteric nature, they differ significantly in their maximum covalency due to the presence of d-orbitals in Aluminium.

### Final Answer:
Beryllium and Aluminium exhibit many properties which are similar, but the two elements differ in their maximum covalency in compounds, with Beryllium showing a maximum covalency of +2 and Aluminium showing +3.

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