Which of the following are not d- block elements ?

Options

A. `[Xe] 5d^(1) 6s^(2)`
B. `[Rn] 6d^(1) 6s^(2)`
C. `[Xe] 4f^(1) 5d^(1) 6s^(2)`
D. `[Rn] 5d^(2) 7s^(2)`

Explanation

To determine which of the following are not d-block elements, we need to understand the definition of d-block elements and apply it to the given options.

### Step-by-Step Solution:

1. **Understand d-block Elements**:
- d-block elements are those elements in which the last electron enters the d-subshell. This includes transition metals found in groups 3 to 12 of the periodic table.

2. **Identify the Given Options**:
- The question provides specific elements or compounds to analyze. For this example, we will consider hypothetical options (Xenon 5d16s2, Rn 6d16s2, Xenon 4f15d16s2, Rn 5d27s2).

3. **Analyze Each Option**:
- **Xenon 5d16s2**:
- The last electron enters the 5d subshell. Therefore, this is a d-block element.
- **Rn 6d16s2**:
- The last electron enters the 6d subshell. Therefore, this is also a d-block element.
- **Xenon 4f15d16s2**:
- The last electron enters the 5d subshell, but since there is an f orbital (4f) being filled as well, this element is primarily considered an f-block element, not a d-block element.
- **Rn 5d27s2**:
- The last electron enters the 5d subshell. However, if we consider its atomic number (which would be around 90), this is also classified as an f-block element.

4. **Conclusion**:
- The elements that are not d-block elements from the given options are **Xenon 4f15d16s2** and **Rn 5d27s2**.

### Final Answer:
- The elements that are not d-block elements are **Xenon 4f15d16s2** and **Rn 5d27s2**.