The diamagnetic species among the following is:
`Cu^(2+) , Cr^(3+), Co^(3+) , Cd^(2+)`

Options

A. `Cu^(2+)`
B. `Cd^(2+)`
C. `Cr^(3+)`
D. `Co^(3+)`

Explanation

To determine which of the given species is diamagnetic, we need to analyze the electronic configurations of each ion and check for unpaired electrons. A diamagnetic species has all its electrons paired, while a paramagnetic species has at least one unpaired electron.

### Step-by-Step Solution:

1. **Identify the electronic configuration of each element in its ground state:**
- **Copper (Cu)**: The ground state configuration is \( [Ar] 3d^{10} 4s^1 \).
- **Chromium (Cr)**: The ground state configuration is \( [Ar] 3d^5 4s^1 \).
- **Cobalt (Co)**: The ground state configuration is \( [Ar] 3d^7 4s^2 \).
- **Cadmium (Cd)**: The ground state configuration is \( [Kr] 4d^{10} 5s^2 \).

2. **Determine the electronic configuration of the ions:**
- **Copper (Cu\(^{2+}\))**: Remove 2 electrons (1 from 4s and 1 from 3d):
\[ \text{Cu}^{2+}: [Ar] 3d^9 \]
- **Chromium (Cr\(^{3+}\))**: Remove 3 electrons (1 from 4s and 2 from 3d):
\[ \text{Cr}^{3+}: [Ar] 3d^3 \]
- **Cobalt (Co\(^{3+}\))**: Remove 3 electrons (2 from 4s and 1 from 3d):
\[ \text{Co}^{3+}: [Ar] 3d^6 \]
- **Cadmium (Cd\(^{2+}\))**: Remove 2 electrons (2 from 5s):
\[ \text{Cd}^{2+}: [Kr] 4d^{10} \]

3. **Check for unpaired electrons:**
- **Cu\(^{2+}\)**: \(3d^9\) has 1 unpaired electron (paramagnetic).
- **Cr\(^{3+}\)**: \(3d^3\) has 3 unpaired electrons (paramagnetic).
- **Co\(^{3+}\)**: \(3d^6\) has 4 unpaired electrons (paramagnetic).
- **Cd\(^{2+}\)**: \(4d^{10}\) has all electrons paired (diamagnetic).

4. **Conclusion**: The only diamagnetic species among the given options is **Cd\(^{2+}\)**.

### Final Answer:
The diamagnetic species among the following is: **Cd\(^{2+}\)**.