Which of the following point defects are shown by AgBr(s) crystals ?
(A) Schottky defect (B) Frenkel defect
(C) Metal excess defect (D) Metal deficiency defect.

Options

A. (A) and (B)
B. (C) and (D)
C. (A) and (C)
D. (B) and (D)

Explanation

To determine which point defects are shown by AgBr(s) crystals, we will analyze each option provided in the question step by step.

### Step 1: Understand the Types of Point Defects
1. **Schottky Defect**: This defect occurs when there are missing ions from the crystal lattice. It results in vacancies that maintain electrical neutrality in the crystal.
2. **Frenkel Defect**: This defect occurs when an ion is displaced from its normal lattice position to an interstitial site, creating a vacancy at the original position.
3. **Metal Excess Defect**: This defect arises when there are more positive ions than negative ions. It can occur due to anionic vacancies or the presence of extra cations in interstitial sites.
4. **Metal Deficiency Defect**: This defect occurs when there are fewer positive ions than negative ions. It can arise from cationic vacancies or extra anions occupying interstitial sites.

### Step 2: Analyze AgBr(s) Crystals
- **AgBr** consists of silver ions (Ag⁺) and bromide ions (Br⁻).
- In AgBr, both Ag⁺ and Br⁻ ions can be missing from their lattice positions, which indicates the presence of Schottky defects.
- Additionally, Ag⁺ ions are relatively mobile and can move to interstitial sites, leading to the formation of Frenkel defects.

### Step 3: Conclusion
Based on the analysis:
- **AgBr(s) crystals exhibit both Schottky and Frenkel defects**. Therefore, the correct answer is (A) Schottky defect and (B) Frenkel defect.

### Final Answer
The point defects shown by AgBr(s) crystals are:
**(A) Schottky defect and (B) Frenkel defect.**

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