Which of the ions is colourless inspite of the presence of unpaired electrons ?

Options

A. `La^(3+)`
B. `Eu^(3+)`
C. `Gd^(3+)`
D. `Lu^(3+)`

Answer

C

Explanation

Gadolinium does not absorb light in the visible region of the spectrum , hence it is colourless inspite of the presence of 7 unpaired electrons . Being colourless , gadolium is sometimes used as a support for other rate earth phosphors and luminesce in the knowledge that it will not quench their intense colour.