Q. Which of the following complex ions is expected to absorb visible light? (At. no. Zn = 30, Sc = 21, Ti = 22, Cr = 24)
A) [Ti(en)₂(NH₃)₂]⁴⁺
B) [Cr(NH₃)₆]³⁺
C) [Zn(NH₃)₆]²⁺
D) [Sc(H₂O)₃(NH₃)₃]³⁺
Explanation
[Solution from source] Cr³⁺ is 3d³, so d–d transitions are possible and the complex absorbs visible light. Ti⁴⁺ and Sc³⁺ are 3d⁰ and Zn²⁺ is 3d¹⁰, so they have no d–d transitions and are colourless. Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.