State true or False
Solid `KCl` is a good conductor of electricity.

Explanation

To determine whether the statement "Solid KCl is a good conductor of electricity" is true or false, we can analyze the properties of solid KCl.

### Step-by-Step Solution:

1. **Understanding Conductivity**:
- Conductivity in materials is primarily due to the movement of charged particles, such as ions or electrons. For a substance to conduct electricity, it must have free-moving charged particles.

2. **Structure of Solid KCl**:
- KCl (potassium chloride) is an ionic compound. In its solid state, KCl forms a crystalline lattice structure where potassium ions (K⁺) and chloride ions (Cl⁻) are held together by strong ionic bonds.

3. **Mobility of Ions in Solid State**:
- In solid KCl, the ions are fixed in place within the crystal lattice. They do not have the freedom to move around because they are tightly bound by the ionic bonds. This lack of mobility means that there are no free-moving charged particles available to conduct electricity.

4. **Comparison with Liquid KCl**:
- It is important to note that when KCl is melted (in liquid form) or dissolved in water (aqueous solution), the ionic bonds are broken, allowing the ions to move freely. In these states, KCl can conduct electricity.

5. **Conclusion**:
- Since solid KCl does not allow for the movement of ions, it cannot conduct electricity. Therefore, the statement "Solid KCl is a good conductor of electricity" is **False**.

### Final Answer:
**False**