Which of the following is a covalent solid ?

Options

A. `CO_(2)(s)`
B. `H_(2)O(s)`
C. Diamond
D. NaCl(s)

Answer

To determine which of the given options is a covalent solid, we need to analyze each substance based on its bonding characteristics.

### Step-by-Step Solution:

1. **Identify the Options**: The options provided are:
- CO₂ (solid)
- H₂O (solid)
- Diamond
- NaCl (solid)

2. **Define Covalent Solid**: A covalent solid is characterized by a three-dimensional network of atoms held together by covalent bonds. There are no intermolecular forces or ionic bonds present in a covalent solid.

3. **Analyze CO₂ (solid)**:
- CO₂ is a molecular solid. It consists of discrete CO₂ molecules held together by intermolecular forces (van der Waals forces). Therefore, it is **not a covalent solid**.

4. **Analyze H₂O (solid)**:
- H₂O (ice) is also a molecular solid. It consists of water molecules held together by hydrogen bonds, which are a type of intermolecular force. Thus, it is **not a covalent solid**.

5. **Analyze NaCl (solid)**:
- NaCl is an ionic solid. It consists of sodium ions (Na⁺) and chloride ions (Cl⁻) held together by ionic bonds. Therefore, it is **not a covalent solid**.

6. **Analyze Diamond**:
- Diamond is a covalent solid. It consists of carbon atoms that are bonded to each other in a three-dimensional network through covalent bonds. There are no intermolecular forces present, making diamond a true covalent solid.

7. **Conclusion**: Among the given options, **diamond** is the only covalent solid.

### Final Answer:
**Diamond** is a covalent solid.

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