Which of following will not conduct electricity?

Options

A. KOH (aq.)
B. Fused NaCl
C. Solid KCl
D. Graphite

Answer

To determine which of the given substances will not conduct electricity, we need to analyze each option based on their ability to produce ions or free electrons, which are necessary for electrical conduction.

### Step-by-Step Solution:

1. **Understanding Electrical Conductivity**:
- Substances that can conduct electricity must contain free-moving charged particles, such as ions or free electrons.

2. **Analyzing Each Option**:
- **Option 1: KOH (aqueous)**
- When potassium hydroxide (KOH) is dissolved in water, it dissociates into potassium ions (K⁺) and hydroxide ions (OH⁻).
- Since it produces ions, KOH (aqueous) can conduct electricity.

- **Option 2: Fused NaCl (sodium chloride)**
- Fused NaCl means that sodium chloride is melted, allowing it to dissociate into sodium ions (Na⁺) and chloride ions (Cl⁻).
- The presence of these ions means that fused NaCl can also conduct electricity.

- **Option 3: Solid KCl (potassium chloride)**
- In its solid state, KCl does not dissociate into ions. The ions are held in a fixed lattice structure and cannot move freely.
- Therefore, solid KCl does not conduct electricity.

- **Option 4: Graphite**
- Graphite is an allotrope of carbon that has a structure allowing free electrons to move between layers.
- These free electrons enable graphite to conduct electricity.

3. **Conclusion**:
- Among the options given, the substance that does not conduct electricity is **solid KCl**.

### Final Answer:
The correct option is **solid KCl**.

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