Which of the following ion is likely to form white complexes

Options

A. `Cd^(2+)`
B. `Ti^(3+)`
C. `Cr^(3+)`
D. none of the above

Answer

To determine which ion is likely to form white complexes, we need to analyze the electronic configurations of the given ions: Cd²⁺, Ti³⁺, and Cr³⁺.

### Step-by-Step Solution:

1. **Identify the Ions**:
- The ions in question are:
- Cadmium (Cd²⁺)
- Titanium (Ti³⁺)
- Chromium (Cr³⁺)

2. **Determine the Electronic Configuration**:
- **Cadmium (Cd)**:
- Atomic number = 48
- Electronic configuration = [Kr] 4d¹⁰ 5s²
- For Cd²⁺, we remove 2 electrons:
- Cd²⁺: [Kr] 4d¹⁰
- **Titanium (Ti)**:
- Atomic number = 22
- Electronic configuration = [Ar] 4s² 3d²
- For Ti³⁺, we remove 3 electrons (2 from 4s and 1 from 3d):
- Ti³⁺: [Ar] 3d¹
- **Chromium (Cr)**:
- Atomic number = 24
- Electronic configuration = [Ar] 4s² 3d⁴
- For Cr³⁺, we remove 3 electrons (1 from 4s and 2 from 3d):
- Cr³⁺: [Ar] 3d³

3. **Analyze the Electron Configurations**:
- **Cd²⁺**: The 4d subshell is completely filled (4d¹⁰). A completely filled d-subshell does not participate in d-d transitions, which are responsible for color in transition metal complexes. Therefore, Cd²⁺ is expected to form colorless or white complexes.
- **Ti³⁺**: With a 3d¹ configuration, Ti³⁺ has unpaired electrons and is paramagnetic, indicating that it can show color in complexes.
- **Cr³⁺**: With a 3d³ configuration, Cr³⁺ also has unpaired electrons and is paramagnetic, indicating that it can show color in complexes.

4. **Conclusion**:
- Among the given ions, **Cd²⁺** is the only ion that is likely to form white complexes due to its completely filled d-orbitals, which do not allow for d-d transitions that would result in color.

### Final Answer:
**Cd²⁺ is likely to form white complexes.**