Which of the following is not a periodic property?

Options

A. Density
B. Atomic volume
C. Atomic radii
D. Ionisation potential

Explanation

To solve the question "Which of the following is not a periodic property?" we need to analyze each of the given options in terms of their behavior in the periodic table.

### Step-by-Step Solution:

1. **Understand Periodic Properties**: Periodic properties are characteristics of elements that show a predictable trend when moving across a period or down a group in the periodic table. Common periodic properties include atomic radius, ionization energy, and atomic volume.

2. **Analyze Each Option**:
- **Atomic Radius**:
- Trend: Increases down a group and decreases across a period from left to right.
- Conclusion: This is a periodic property.

- **Atomic Volume**:
- Trend: Similar to atomic radius, atomic volume increases down a group and decreases across a period.
- Conclusion: This is also a periodic property.

- **Ionization Potential (Ionization Energy)**:
- Trend: Increases across a period from left to right and decreases down a group.
- Conclusion: This is a periodic property as well.

- **Density**:
- Trend: Density does not show a consistent trend across periods or groups. It can vary significantly based on the type of element and its state (solid, liquid, gas).
- Conclusion: Density does not qualify as a periodic property.

3. **Final Decision**: Based on the analysis, the option that is not a periodic property is **Density**.

### Answer:
The correct answer is **Density**.

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