The trend common to both the group 2 and 16 elements in the periodic table is that with increases in atomic number

Options

A. a maximum valency increase
B. atomic radius increases
C. reactivity remains constant
D. basic strength of hydroxides decreases.

Explanation

To solve the question regarding the common trend in Group 2 and Group 16 elements in the periodic table with increasing atomic number, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Groups**: Recognize that Group 2 elements are alkaline earth metals (e.g., Beryllium, Magnesium, Calcium) and Group 16 elements are chalcogens (e.g., Oxygen, Sulfur, Selenium).

2. **Understand the Trend with Atomic Number**: As we move down both groups (from top to bottom), we need to analyze how certain properties change with increasing atomic number.

3. **Consider Atomic Radius**: One of the most significant trends observed in both groups is the increase in atomic radius. As we move down the groups, additional electron shells are added, which increases the distance of the outermost electrons from the nucleus.

4. **Evaluate Other Options**:
- **Maximum Valence Increase**: This is incorrect because while the maximum oxidation state may change, it does not consistently increase in both groups.
- **Reactivity Remains Constant**: This is also incorrect as reactivity varies in both groups with increasing atomic number.
- **Basic Strength of Hydroxides Decreases**: This is incorrect for Group 2, where basic strength actually increases down the group.

5. **Conclusion**: The only common trend for both Group 2 and Group 16 elements as atomic number increases is that the atomic radius increases.

### Final Answer:
The trend common to both Group 2 and Group 16 elements in the periodic table is that with increases in atomic number, the atomic radius increases.

---