Question

In following pairs, the one in which both transition metal ions are colourless is :

• A. Sc³⁺, Zn²⁺
• B. Ti⁴⁺, Cu²⁺
• C. V²⁺, Ti³⁺
• D. Zn²⁺, Mn²⁺

Answer 1

The Correct Option is A

Scandium ions (Sc⁺³) and zinc ions (Zn⁺²) are colorless due to the absence of unpaired electrons. In contrast, transition metal ions such as copper ions (Cu⁺²), titanium ions (Ti⁺³), vanadium ions (V⁺²), and manganese ions (Mn⁺²) exhibit color as they possess unpaired electrons.
When these transition metal ions absorb light in the visible region, an unpaired electron from a lower energy d orbital is excited to a higher energy d orbital. The observed color is complementary to the absorbed light frequency.
So, the correct option is (A): Sc³⁺, Zn²⁺