Ammonia will not form complex with

Options

A. `Ag^(2+)`
B. `Pb^(2+)`
C. `Cu^(2+)`
D. `Cd^(2+)`

Explanation

To determine which metal ion ammonia will not form a complex with, we need to analyze the electronic configurations of the given metal ions and their ability to accept electron pairs from ammonia.

### Step-by-Step Solution:

1. **Identify the Metal Ions**: The given metal ions are Pb²⁺ (Lead), Cu²⁺ (Copper), Ag²⁺ (Silver), and Cd²⁺ (Cadmium).

2. **Determine the Electronic Configurations**:
- **Lead (Pb²⁺)**: The electronic configuration of Pb is [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p². When it loses two electrons to become Pb²⁺, it loses the two 6p electrons, resulting in [Xe] 4f¹⁴ 5d¹⁰ 6s². This configuration shows that all d and s orbitals are filled, meaning there are no vacant orbitals to accept electron pairs.
- **Copper (Cu²⁺)**: The electronic configuration of Cu is [Ar] 3d¹⁰ 4s¹. When it loses two electrons to become Cu²⁺, it loses the 4s electron and one from the 3d, resulting in [Ar] 3d⁹. The presence of a partially filled d orbital indicates that Cu²⁺ can accept electron pairs and form complexes.
- **Silver (Ag²⁺)**: The electronic configuration of Ag is [Kr] 4d¹⁰ 5s¹. For Ag²⁺, it loses the 5s electron and one from the 4d, resulting in [Kr] 4d⁹. Similar to Cu²⁺, Ag²⁺ has a partially filled d orbital, allowing it to form complexes.
- **Cadmium (Cd²⁺)**: The electronic configuration of Cd is [Kr] 4d¹⁰ 5s². Upon losing two electrons to become Cd²⁺, it loses the 5s electrons, resulting in [Kr] 4d¹⁰. Although the d orbital is fully filled, Cd²⁺ can still form complexes with ligands like ammonia.

3. **Conclusion**: Among the given metal ions, Pb²⁺ has no vacant orbitals to accept the lone pair from ammonia, hence ammonia will not form a complex with Pb²⁺.

### Final Answer:
Ammonia will not form a complex with **Pb²⁺ (Lead)**.