Question
Explain why $Gd ^{3+}$ is colourless.

Answer

$Gd^{3+}$ has electronic configuration, $[Xe] 4f^7$
Due to extra stability of half filled orbital, it does not allow $f \rightarrow f$ transition, and hence does not absorb radiations in the visible region.
Hence $Gd^{3+}$ is colourless.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free