Iodine molecules are held in the crystal lattice by:

Options

A. London forces
B. dipole -dipole interactions
C. covalent bonds
D. coulombic forces

Answer

To solve the question regarding how iodine molecules are held in the crystal lattice, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Nature of Iodine Molecules**:
- Iodine (I₂) is a diatomic molecule composed of two iodine atoms. It is a non-polar molecule due to the equal sharing of electrons between the two identical iodine atoms.

**Hint**: Remember that non-polar molecules have no permanent dipole moment.

2. **Understand the Type of Solid**:
- Iodine forms a molecular solid in its crystalline form. In molecular solids, the particles are held together by intermolecular forces rather than covalent or ionic bonds.

**Hint**: Different types of solids (ionic, covalent, metallic, molecular) have different types of bonding forces.

3. **Identify the Intermolecular Forces**:
- The primary intermolecular force present in non-polar molecules like iodine is the London dispersion force (also known as London forces). These forces arise due to temporary dipoles that occur when electron distributions around molecules fluctuate.

**Hint**: London dispersion forces are the weakest type of intermolecular force and are significant in non-polar substances.

4. **Evaluate the Other Options**:
- **Dipole-Dipole Interactions**: These occur between polar molecules, which iodine is not.
- **Covalent Bonds**: These are strong bonds that hold atoms together within a molecule, not between molecules in a solid.
- **Coulombic Forces**: These are attractive forces between charged particles, relevant in ionic solids, not in molecular solids like iodine.

**Hint**: Assess each option based on the type of bonding and the nature of the molecules involved.

5. **Conclusion**:
- Since iodine molecules are held together in the crystal lattice by London dispersion forces, the correct answer is that iodine molecules are held in the crystal lattice by **London forces**.

### Final Answer:
Iodine molecules are held in the crystal lattice by **London forces**.