Which of the following ions does not have pseudoinert gas configuration ?

Options

A. `Zn^(2+)`
B. `Sc^(3+)`
C. `Ag^(+)`
D. `Cd^(2+)`.

Answer

To determine which of the following ions does not have a pseudoinert gas configuration, we will analyze the electronic configurations of the given ions. The pseudoinert gas configuration is characterized by having a total of 18 electrons in the outermost shell, which includes fully filled s, p, and d orbitals.

### Step-by-Step Solution:

1. **Identify the Ions**: The ions we need to analyze are:
- Zinc (Zn²⁺)
- Scandium (Sc³⁺)
- Silver (Ag⁺)
- Cadmium (Cd²⁺)

2. **Determine Atomic Numbers**:
- Zinc (Zn) has an atomic number of 30.
- Scandium (Sc) has an atomic number of 21.
- Silver (Ag) has an atomic number of 47.
- Cadmium (Cd) has an atomic number of 48.

3. **Calculate the Electron Configurations**:
- **Zinc (Zn²⁺)**:
- Atomic number = 30 → Electronic configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s²
- Zn²⁺ loses 2 electrons from 4s: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ (28 electrons).
- This configuration is pseudoinert gas because all orbitals are filled.

- **Scandium (Sc³⁺)**:
- Atomic number = 21 → Electronic configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹ 4s²
- Sc³⁺ loses 3 electrons (2 from 4s and 1 from 3d): 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁰ 4s⁰ (18 electrons).
- This configuration is **not** pseudoinert gas because the 3d orbital is empty.

- **Silver (Ag⁺)**:
- Atomic number = 47 → Electronic configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 4d¹⁰ 5s¹
- Ag⁺ loses 1 electron from 5s: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 4d¹⁰ (46 electrons).
- This configuration is pseudoinert gas because all orbitals are filled.

- **Cadmium (Cd²⁺)**:
- Atomic number = 48 → Electronic configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 4d¹⁰ 5s²
- Cd²⁺ loses 2 electrons from 5s: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 4d¹⁰ (46 electrons).
- This configuration is pseudoinert gas because all orbitals are filled.

4. **Conclusion**:
- The ion that does not have a pseudoinert gas configuration is **Scandium (Sc³⁺)**.

### Final Answer:
**Scandium (Sc³⁺)** does not have a pseudoinert gas configuration.