Cations are present in the interstitial sites in …………… .

Options

A. Frenkel defect
B. Schottky defect
C. Vacancy defect
D. metal deficiency defect

Explanation

To solve the question regarding where cations are present in interstitial sites, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Types of Defects**:
- There are two main types of point defects in ionic solids: Schottky defect and Frenkel defect.

2. **Schottky Defect**:
- In a Schottky defect, there is an equal number of cations and anions missing from their lattice sites. This defect does not involve cations occupying interstitial sites. Instead, it results in vacancies where both types of ions are missing.

3. **Frenkel Defect**:
- In a Frenkel defect, a cation (usually smaller in size) leaves its original lattice site and occupies an interstitial site. This means that in this type of defect, cations are indeed present in the interstitial sites.

4. **Conclusion**:
- Based on the definitions and characteristics of the defects, we conclude that cations are present in the interstitial sites in the case of a **Frenkel defect**.

### Final Answer:
Cations are present in the interstitial sites in **Frenkel defect**.

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