Question

The metal which does not form coloured compounds is

• A. Cr
• B. Fe
• C. Zn
• D. Mn

Answer 1

The Correct Option is C

To determine which metal does not form colored compounds, let's consider the electronic configuration and the chemistry of the given options: Cr, Fe, Zn, and Mn.

1. **Chromium (Cr) and its Compounds**:
Chromium often forms colored compounds because it has unpaired electrons in its d-orbitals. For example, Cr³⁺ (chromic ion) can form green-colored compounds like chromium oxide.

2. **Iron (Fe) and its Compounds**:
Iron also forms colored compounds due to its transition metal nature. Fe²⁺ and Fe³⁺ ions often produce colors, like the green color of ferrous sulfate (FeSO₄).

3. **Manganese (Mn) and its Compounds**:
Manganese has various oxidation states, leading to colorful compounds. For example, KMnO₄ (potassium permanganate) is purple.

4. **Zinc (Zn) and its Compounds**:
Zinc is a d-block element, but it has a completely filled d-orbital (3d¹⁰ electronic configuration). Due to the lack of unpaired d-electrons, zinc compounds are generally colorless. Zn²⁺ ions do not absorb visible light, and therefore, no color is observed.

Conclusion: Zinc does not form colored compounds because it lacks unpaired electrons in its d-orbitals, making it the correct answer.