The group of elements in which the last electron is present the anti-penultimate shell of atom called

Options

A. f-block elements
B. d - block elements
C. p-block elements
D. s-block elements

Answer

To determine the group of elements in which the last electron is present in the anti-penultimate shell of an atom, we need to analyze the definitions and configurations of different blocks of elements in the periodic table.

### Step-by-Step Solution:

1. **Understanding Shells and Subshells**:
- The electron configuration of an atom is organized in shells and subshells. The principal quantum number (n) indicates the shell, while the subshells are designated as s, p, d, and f.

2. **Identifying the Anti-Penultimate Shell**:
- The anti-penultimate shell refers to the shell that is one level below the outermost shell. For example, if the outermost shell is n, the anti-penultimate shell would be (n-1).

3. **Identifying the Last Electron**:
- The last electron refers to the most recently added electron in the electron configuration of an atom.

4. **Understanding the Blocks of Elements**:
- The periodic table is divided into four main blocks based on the subshell that receives the last electron:
- **s-block**: Last electron in s subshell (n s^1 or n s^2)
- **p-block**: Last electron in p subshell (n p^1 to n p^6)
- **d-block**: Last electron in d subshell (n-1 d^1 to n-1 d^10)
- **f-block**: Last electron in f subshell (n-2 f^1 to n-2 f^14)

5. **Conclusion**:
- The question specifies the last electron being in the anti-penultimate shell, which corresponds to the f subshell. Therefore, the group of elements in which the last electron is present in the anti-penultimate shell is known as **f-block elements**.

### Final Answer:
The group of elements in which the last electron is present in the anti-penultimate shell of an atom is called **f-block elements**.