Which of the following cannot be regarded as molecular solid ?

Options

A. SiC (Silicon carbide)
B. AIN
C. Diamond
D. `I_(2)`.

Explanation

To determine which of the following cannot be regarded as a molecular solid, we need to analyze each option based on their bonding characteristics and structure.

### Step 1: Analyze Silicon Carbide (SiC)
- Silicon carbide is a compound formed from silicon and carbon.
- It has a strong covalent bond between silicon and carbon atoms.
- The structure of silicon carbide is a network solid, meaning it forms a continuous network of covalent bonds.
- **Conclusion**: Silicon carbide is not a molecular solid; it is a covalent or network solid.

### Step 2: Analyze Aluminum Nitride (AlN)
- Aluminum nitride consists of aluminum and nitrogen.
- Similar to silicon carbide, aluminum nitride has strong covalent bonds between aluminum and nitrogen atoms.
- It also forms a network structure due to these covalent bonds.
- **Conclusion**: Aluminum nitride is not a molecular solid; it is a covalent solid.

### Step 3: Analyze Diamond
- Diamond is a form of carbon where each carbon atom is tetrahedrally bonded to four other carbon atoms.
- The bonds in diamond are strong covalent bonds, creating a three-dimensional network.
- **Conclusion**: Diamond is not a molecular solid; it is a covalent or network solid.

### Step 4: Analyze Iodine (I2)
- Iodine exists as diatomic molecules (I2).
- The molecules are held together by weak intermolecular forces known as London dispersion forces.
- These weak forces allow iodine to be classified as a molecular solid.
- **Conclusion**: Iodine (I2) is a molecular solid.

### Final Conclusion
Based on the analysis:
- Silicon carbide (SiC), aluminum nitride (AlN), and diamond cannot be regarded as molecular solids.
- Only iodine (I2) can be classified as a molecular solid.

### Answer
The substances that cannot be regarded as molecular solids are **Silicon Carbide (SiC), Aluminum Nitride (AlN), and Diamond**.

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