Question

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

• A. \( V^{2+}, Ti^{3+} \)
• B. \( Zn^{2+}, Mn^{2+} \)
• C. \( Ti^{4+}, Cu^{2+} \)
• D. \( Sc^{3+}, Zn^{2+} \)

Hint:

Transition metal ions with completely filled d-orbitals or empty d-orbitals typically do not exhibit colour. They are colourless.

Answer 1

The Correct Option is D

- \( Sc^{3+} \) and \( Zn^{2+} \) are both colourless because they have no unpaired electrons in their d-orbitals, which means they do not absorb visible light. - In other cases like \( V^{2+}, Ti^{3+} \), and \( Ti^{4+}, Cu^{2+} \), the ions have unpaired electrons in their d-orbitals, which are responsible for absorbing light and thus exhibiting colour.
Thus, the correct answer is 4) \( Sc^{3+}, Zn^{2+} \).