The lattice site in a pure crystal cannot be occupied by

Options

A. molecule
B. ion
C. electron
D. atom

Explanation

To solve the question "The lattice site in a pure crystal cannot be occupied by," we need to understand the concept of lattice sites in the context of solid-state chemistry.

### Step-by-Step Solution:

1. **Understanding Lattice Sites**:
- A lattice site is defined as a point in a crystal lattice where an atom, ion, or molecule can be located. In a crystal structure, these points are arranged in a regular pattern.

2. **Composition of Lattice Sites**:
- In a pure crystal, the lattice sites are typically occupied by the same type of atoms, ions, or molecules that make up the crystal. For example, in a pure sodium chloride (NaCl) crystal, the lattice sites are occupied by Na⁺ and Cl⁻ ions.

3. **Identifying What Cannot Occupy Lattice Sites**:
- The question asks what cannot occupy these lattice sites in a pure crystal. Since lattice sites are specifically meant for atoms, ions, or molecules, we need to consider what does not fit this description.

4. **Considering Electrons**:
- Electrons are subatomic particles and do not occupy lattice sites in the same way that atoms or ions do. They exist in the electron cloud surrounding the nucleus of an atom and can only occupy a lattice site if there is a vacancy, which would indicate that the crystal is not pure.

5. **Conclusion**:
- Therefore, the correct answer to the question is that the lattice site in a pure crystal cannot be occupied by electrons.

### Final Answer:
The lattice site in a pure crystal cannot be occupied by **electrons**.

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