Which of the following is not a similarly of beryllium with aluminium?

Options

A. It becomes passive when treated with conc. `HNO_(3)`.
B. It forms polymerric covalent hydrides
C. Carbonate of Be is extremely stable
D. saltts of Be do not impart colour to the flame.

Answer

To solve the question "Which of the following is not a similarity of beryllium with aluminium?", we will analyze each option provided and determine which statement does not hold true for both elements.

### Step-by-Step Solution:

1. **Understanding the Question**: We need to identify which of the given options is not a similarity between beryllium (Be) and aluminium (Al).

2. **Analyzing Option A**:
- **Statement**: "It becomes passive when treated with concentrated HNO3."
- **Explanation**: Both beryllium and aluminium form a protective oxide layer when exposed to concentrated nitric acid (HNO3), which prevents further reaction. This is a similarity.
- **Conclusion**: This option is a similarity.

3. **Analyzing Option B**:
- **Statement**: "It forms polymeric covalent hydrate."
- **Explanation**: Both beryllium hydride (BeH2) and aluminium hydride (AlH3) are known to form polymeric structures. This indicates that they share this characteristic.
- **Conclusion**: This option is also a similarity.

4. **Analyzing Option C**:
- **Statement**: "Carbonate of beryllium is extremely stable."
- **Explanation**: Beryllium carbonate (BeCO3) is not stable and tends to decompose. In contrast, aluminium carbonate (Al2(CO3)3) is more stable. Therefore, this statement does not hold true for beryllium.
- **Conclusion**: This option is not a similarity and is the correct answer to the question.

5. **Analyzing Option D**:
- **Statement**: "Salts of beryllium do not impart color to the flame."
- **Explanation**: Beryllium salts do not produce a flame color due to their high ionization enthalpy, which prevents excitation of electrons. This is a similarity with aluminium, which also does not impart color to the flame.
- **Conclusion**: This option is a similarity.

### Final Answer:
The option that is not a similarity of beryllium with aluminium is **Option C: "Carbonate of beryllium is extremely stable."**