Which one of the following material conducts electricity?

Options

A. Crystalline potassium chloride
B. Fused sulphates
C. Molten sodium chlroide
D. Diamond

Explanation

To determine which material conducts electricity, we need to consider the nature of the materials listed in the options. Here's a step-by-step solution:

### Step 1: Understand the Concept of Electrical Conductivity
Electrical conductivity occurs when charged particles (ions or electrons) are free to move. In solids, typically only metals can conduct electricity due to the mobility of electrons. In ionic compounds, conductivity is observed when they are in molten form or dissolved in water, as the ions are free to move.

**Hint:** Remember that only free-moving charged particles can conduct electricity.

### Step 2: Analyze the Options
We will evaluate each option to see if they contain free-moving ions or electrons.

1. **Fused Sulfates**: When sulfates are fused, they may contain ions, but they do not conduct electricity in their fused state.

**Hint:** Check if the ions are free to move in the state given (fused or solid).

2. **Diamond**: This is an allotrope of carbon and is in elemental form. It does not have free-moving ions or electrons, hence it cannot conduct electricity.

**Hint:** Allotropes of nonmetals like carbon (in forms like diamond) usually do not conduct electricity.

3. **Crystalline Potassium Chloride (KCl)**: In its crystalline form, KCl has tightly bound ions (K⁺ and Cl⁻) that cannot move freely. Therefore, it does not conduct electricity in this state.

**Hint:** Consider the arrangement of ions in a crystalline lattice and their mobility.

4. **Molten Sodium Chloride (NaCl)**: When NaCl is melted, the Na⁺ and Cl⁻ ions are free to move. This allows molten NaCl to conduct electricity.

**Hint:** Look for states where ions can move freely, such as molten or aqueous solutions.

### Step 3: Conclusion
After analyzing all the options, we find that the only material that conducts electricity is **molten sodium chloride (NaCl)**, where the ions are free to move.

**Final Answer:** The material that conducts electricity is **molten sodium chloride (NaCl)**.