Which of the following set has all the ions coloured ?

Options

A. `Cu^(2+),Fe^(2+), Co^(2+)`
B. `Cu^(2+), Sc^(3+), Mg^(2+)`
C. `Al^(3+), Zn^(2+), Co^(2+)`
D. `Fe^(3+), Sc^(3+), Ni^(2+)`

Answer

To determine which set of ions contains all colored ions, we need to analyze the electronic configurations of the ions in each set. Colored ions typically have partially filled d-orbitals, which allow for electronic transitions that absorb visible light.

### Step-by-Step Solution:

1. **Understanding Color in Ions**:
- Ions are colored when they have unpaired electrons in their d-orbitals.
- Ions with completely filled d-orbitals (d^0 or d^10) are colorless.

2. **Analyzing the First Set (Cu²⁺, Fe²⁺, Co²⁺)**:
- **Cu²⁺**: Electronic configuration is [Ar] 3d⁹ (9 electrons in the d-orbital) → colored.
- **Fe²⁺**: Electronic configuration is [Ar] 3d⁶ (6 electrons in the d-orbital) → colored.
- **Co²⁺**: Electronic configuration is [Ar] 3d⁷ (7 electrons in the d-orbital) → colored.
- **Conclusion**: All ions in this set are colored.

3. **Analyzing the Second Set (Cu²⁺, Sc³⁺, Mg²⁺)**:
- **Cu²⁺**: Colored as established above.
- **Sc³⁺**: Electronic configuration is [Ar] 3d⁰ (0 electrons in the d-orbital) → colorless.
- **Mg²⁺**: Electronic configuration is [Ne] (no d-electrons) → colorless.
- **Conclusion**: Not all ions are colored.

4. **Analyzing the Third Set (Al³⁺, Zn²⁺, Co²⁺)**:
- **Al³⁺**: Electronic configuration is [Ne] (no d-electrons) → colorless.
- **Zn²⁺**: Electronic configuration is [Ar] 3d¹⁰ (10 electrons in the d-orbital) → colorless.
- **Co²⁺**: Colored as established above.
- **Conclusion**: Not all ions are colored.

5. **Analyzing the Fourth Set (Fe³⁺, Ni²⁺, Sc³⁺)**:
- **Fe³⁺**: Electronic configuration is [Ar] 3d⁵ (5 electrons in the d-orbital) → colored.
- **Ni²⁺**: Electronic configuration is [Ar] 3d⁸ (8 electrons in the d-orbital) → colored.
- **Sc³⁺**: Colorless as established above.
- **Conclusion**: Not all ions are colored.

### Final Answer:
The first set (Cu²⁺, Fe²⁺, Co²⁺) contains all colored ions.