Which substance will conduct the current in the solid state

Options

A. Diamond
B. Graphite
C. Iodine
D. Sodium chloride

Answer

To determine which substance will conduct electricity in the solid state, we need to analyze the properties of each given substance: diamond, graphite, iodine, and sodium chloride.

### Step-by-Step Solution:

1. **Analyze Diamond**:
- Diamond is a form of carbon where each carbon atom is tetrahedrally bonded to four other carbon atoms, forming a rigid three-dimensional structure.
- In this structure, there are no free electrons available to move, which means diamond does not conduct electricity in the solid state.

**Hint**: Remember that the presence of free electrons is essential for electrical conductivity.

2. **Analyze Graphite**:
- Graphite is another allotrope of carbon but has a different structure. It consists of layers of carbon atoms arranged in hexagonal patterns.
- Each carbon atom in graphite is bonded to three other carbon atoms, leaving one electron free. These free electrons can move between the layers, allowing graphite to conduct electricity even in solid form.

**Hint**: Look for materials with delocalized electrons or layered structures, as they often conduct electricity.

3. **Analyze Iodine**:
- Iodine is a molecular solid composed of diatomic molecules (I2). The bonds between iodine atoms are covalent, and there are no free electrons available for conduction.
- Therefore, iodine does not conduct electricity in the solid state.

**Hint**: Covalent bonds in molecular solids typically do not allow for free movement of electrons.

4. **Analyze Sodium Chloride (NaCl)**:
- Sodium chloride is an ionic compound that consists of Na+ and Cl- ions. In the solid state, these ions are held together in a rigid lattice structure.
- While NaCl can conduct electricity when dissolved in water (aqueous state) because the ions dissociate and are free to move, it does not conduct electricity in the solid state as the ions are fixed in place.

**Hint**: Ionic compounds require dissociation into ions to conduct electricity; they do not conduct in solid form.

### Conclusion:
Based on the analysis, the only substance that conducts electricity in the solid state is **graphite**.