At zero kelvin, most of the ionic crystals possess

Options

A. Frenkel defect
B. Schotky defect
C. Metal excess defect
D. No defect

Answer

To solve the question "At zero Kelvin, most of the ionic crystals possess," we need to analyze the properties of ionic crystals and the concept of crystal defects.

### Step-by-Step Solution:

1. **Understanding Crystal Defects:**
- Crystal defects refer to imperfections in the regular arrangement of ions in a crystal lattice. These defects can affect the physical properties of the material.

2. **Types of Crystal Defects:**
- **Frankl Defect:** This occurs when cations are displaced from their lattice positions to interstitial sites, but all lattice positions are still occupied.
- **Skotky Defect:** This defect involves the absence of some cations and anions in the lattice, maintaining the overall charge neutrality.
- **Metal Excess Defect:** This occurs when there is a vacancy of anions, and electrons occupy these vacancies, leading to an excess of metal cations.

3. **Behavior of Ionic Crystals at Absolute Zero (0 Kelvin):**
- At 0 Kelvin, the thermal energy is minimal, and the ions in the crystal lattice are in their lowest energy state. The ions are fixed in their positions and do not have the energy to move or create defects.
- Therefore, at absolute zero, ionic crystals do not exhibit any defects because there is no thermal energy to cause any displacement or vacancy.

4. **Conclusion:**
- Given the analysis, at 0 Kelvin, most ionic crystals possess **no defect**. Thus, the correct answer to the question is option 4: **no defect**.

### Final Answer:
At zero Kelvin, most of the ionic crystals possess **no defect**.

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