Which of the following is not a periodic property

Options

A. Electronegativity
B. Atomic volume
C. Covalent radii
D. Atomic mass

Answer

To determine which of the following is not a periodic property, we need to first understand what periodic properties are and how they behave across the periodic table.

### Step-by-Step Solution:

1. **Define Periodic Properties**: Periodic properties are characteristics of elements that show a regular pattern or trend when arranged in the periodic table. These properties tend to reappear at regular intervals based on the atomic number.

2. **Identify Common Periodic Properties**: Common periodic properties include:
- **Electronegativity**: Tends to increase from left to right across a period and decreases down a group.
- **Atomic Volume**: Generally decreases from left to right across a period and increases down a group.
- **Covalent Radius**: Similar trend to atomic volume; decreases across a period and increases down a group.

3. **Examine Atomic Mass**: Atomic mass does not follow a consistent trend. It can vary irregularly; sometimes it increases, sometimes it decreases, and it does not show a regular pattern like the other properties mentioned.

4. **Conclusion**: Since atomic mass does not exhibit a regular trend and is not consistent across the periodic table, it is not considered a periodic property.

5. **Final Answer**: The property that is not a periodic property is **Atomic Mass**.