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 analyze the options provided and understand the concept of lattice sites in a crystal structure.

### Step-by-Step Solution:

1. **Understanding Lattice Sites**:
- A crystal lattice is a three-dimensional arrangement of points that represent the positions of atoms, ions, or molecules in a crystal. Each point in the lattice is called a lattice site.

2. **Identifying Possible Occupants of Lattice Sites**:
- Lattice sites can be occupied by:
- **Atoms**: These are the basic building blocks of matter and can occupy lattice sites in a crystal.
- **Ions**: Charged particles (cations and anions) can also occupy lattice sites, especially in ionic crystals.
- **Molecules**: In molecular crystals, entire molecules can occupy lattice sites.

3. **Analyzing the Options**:
- Given options are:
- A) Molecule
- B) Ion
- C) Electron
- D) Atom
- From our understanding, options A, B, and D (molecule, ion, and atom) can occupy lattice sites.

4. **Identifying the Incorrect Option**:
- **Electrons**: Electrons are subatomic particles that exist within atoms and do not occupy lattice sites. They are not discrete entities that can be placed at specific points in a crystal lattice. Instead, they are found in orbitals around the nucleus of an atom.

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

### Final Answer:
The lattice site in a pure crystal cannot be occupied by: **Electron (Option C)**.