Which one of the following material conducts electricity?

Options

A. diamond
B. crystalline sodium chloride
C. barium sulphate
D. fused potassium chloride

Explanation

To determine which material conducts electricity among the given options, we will analyze each material based on its structure and the presence of free ions or electrons.

### 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.
- This structure does not allow for the presence of free electrons or ions.
- **Conclusion:** Diamond does not conduct electricity.

2. **Analyze Crystalline Sodium Chloride (NaCl):**
- In its solid state, NaCl forms a rigid lattice structure.
- In this structure, the ions (Na⁺ and Cl⁻) are fixed in place and cannot move freely.
- **Conclusion:** Solid NaCl does not conduct electricity. (It can conduct when molten due to free ions.)

3. **Analyze Barium Sulfate (BaSO₄):**
- Barium sulfate is typically found as a solid precipitate.
- Similar to NaCl, in its solid state, BaSO₄ does not have free ions or electrons to facilitate electrical conductivity.
- **Conclusion:** Barium sulfate does not conduct electricity.

4. **Analyze Fused Potassium Chloride (KCl):**
- When KCl is melted (fused), it breaks down into its constituent ions (K⁺ and Cl⁻), allowing them to move freely.
- The presence of these free-moving ions enables the conduction of electricity.
- **Conclusion:** Fused KCl conducts electricity.

### Final Answer:
The material that conducts electricity among the given options is **fused KCl**.

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