`NaCl` shows Schottky defects and `AgCl` shows Frekel defects. Their electrical conductivity is due to the

Options

A. motion of ions and not the motion of electrons
B. motion of electrons and not the motion of ions
C. lower coordination number of NaCl
D. higher coordinaiton number of AgCl

Answer

To solve the question regarding the electrical conductivity of NaCl and AgCl, we need to understand the types of defects present in these ionic compounds and how they relate to conductivity.

### Step-by-Step Solution:

1. **Identify the Defects**:
- NaCl exhibits **Schottky defects**.
- AgCl exhibits **Frenkel defects**.

2. **Understand Schottky Defects**:
- Schottky defects occur when an equal number of cations and anions are missing from their lattice positions.
- In NaCl, this means that some Na⁺ and Cl⁻ ions are absent from the lattice, creating vacancies.

3. **Electrical Conductivity in NaCl**:
- The electrical conductivity in NaCl is primarily due to the movement of ions (both Na⁺ and Cl⁻) within the crystal lattice.
- When an electric field is applied, these ions can move towards the oppositely charged electrodes, allowing for conductivity.

4. **Understand Frenkel Defects**:
- Frenkel defects occur when a cation leaves its lattice position and occupies an interstitial site, creating a vacancy (or hole) at the original lattice position.
- In AgCl, this means that Ag⁺ ions can move to interstitial sites, leaving behind vacancies.

5. **Electrical Conductivity in AgCl**:
- In AgCl, the electrical conductivity is due to the movement of these vacancies (holes) created by the cation migration.
- The movement of Ag⁺ ions and the holes they leave behind contribute to the overall conductivity.

6. **Conclusion**:
- For NaCl, the electrical conductivity is due to the **motion of ions** (Na⁺ and Cl⁻).
- For AgCl, the electrical conductivity is due to the **motion of holes** created by the movement of Ag⁺ ions.

### Final Answer:
The electrical conductivity of NaCl is due to the motion of ions, while the electrical conductivity of AgCl is due to the motion of holes.