Which is not a molecular solid?

Options

A. copper
B. benzene
C. ice
D. quartz

Explanation

To determine which of the given options is not a molecular solid, we need to understand the characteristics of molecular solids and compare them with the options provided.

### Step-by-Step Solution:

1. **Understanding Molecular Solids**:
- Molecular solids are composed of molecules held together by intermolecular forces such as Van der Waals forces, dipole-dipole interactions, or hydrogen bonding.
- They can be categorized into three types:
- Non-polar molecular solids (e.g., O₂, N₂)
- Polar molecular solids (e.g., CO₂)
- Hydrogen-bonded molecular solids (e.g., H₂O)

2. **Analyzing the Options**:
- **Option 1: Copper (Cu)**:
- Copper is a metal and forms metallic solids. It does not consist of discrete molecules and is not held together by molecular forces. Therefore, it is not a molecular solid.
- **Option 2: Benzene (C₆H₆)**:
- Benzene is a non-polar molecular solid. It consists of discrete molecules held together by Van der Waals forces. Thus, it is a molecular solid.
- **Option 3: Ice (H₂O)**:
- Ice is a hydrogen-bonded molecular solid. It consists of water molecules held together by hydrogen bonds, making it a molecular solid.
- **Option 4: Quartz (SiO₂)**:
- Quartz is a covalent network solid. It consists of a continuous network of Si-O bonds and does not have discrete molecules. Therefore, it is not a molecular solid.

3. **Conclusion**:
- From the analysis, both Copper (Option 1) and Quartz (Option 4) are not molecular solids. However, since the question asks for which is not a molecular solid, we can conclude that:
- **Copper is the primary answer as it is a metal.**

### Final Answer:
**Copper (Cu) is not a molecular solid.**