Which one of the following ions is coloured ?

Options

A. `Sc^(3+)`
B. `Ti^(4+)`
C. `Zn^(2+)`
D. `V^(2+)`

Answer

To determine which of the given ions is colored, we need to analyze the electronic configurations of each ion and check for the presence of unpaired electrons in the d-orbitals. Colored ions typically have unpaired electrons that allow for electronic transitions, which absorb certain wavelengths of light and give rise to color.

### Step-by-Step Solution:

1. **Identify the Ions:**
The ions we need to evaluate are:
- Scandium (Sc³⁺)
- Titanium (Ti⁴⁺)
- Zinc (Zn²⁺)
- Vanadium (V²⁺)

2. **Determine the Electronic Configuration:**
- **Scandium (Sc³⁺):**
- Atomic number of Sc = 21
- Electronic configuration of Sc = [Ar] 3d¹⁵s²
- For Sc³⁺, we remove 3 electrons:
- Configuration = [Ar] 3d⁰ 4s⁰
- This means there are no electrons in the d-orbitals.

- **Titanium (Ti⁴⁺):**
- Atomic number of Ti = 22
- Electronic configuration of Ti = [Ar] 3d² 4s²
- For Ti⁴⁺, we remove 4 electrons:
- Configuration = [Ar] 3d⁰ 4s⁰
- Again, there are no electrons in the d-orbitals.

- **Zinc (Zn²⁺):**
- Atomic number of Zn = 30
- Electronic configuration of Zn = [Ar] 3d¹⁰ 4s²
- For Zn²⁺, we remove 2 electrons:
- Configuration = [Ar] 3d¹⁰ 4s⁰
- The d-orbitals are fully filled (10 electrons).

- **Vanadium (V²⁺):**
- Atomic number of V = 23
- Electronic configuration of V = [Ar] 3d³ 4s²
- For V²⁺, we remove 2 electrons:
- Configuration = [Ar] 3d³ 4s⁰
- There are 3 unpaired electrons in the d-orbitals.

3. **Determine Color:**
- **Sc³⁺:** Colorless (no d-electrons)
- **Ti⁴⁺:** Colorless (no d-electrons)
- **Zn²⁺:** Colorless (fully filled d-orbitals)
- **V²⁺:** Colored (presence of unpaired electrons allows for electronic transitions)

4. **Conclusion:**
The ion that is colored among the given options is **Vanadium (V²⁺)**.

### Final Answer:
The colored ion is **Vanadium (V²⁺)**.

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