Question

Which one of the following compounds is not coloured?

(a) Na₂CuCl₄ 

(b) Na₂CdCl₂

(c) CrH₂O₆Cl₃

(d) all of the above

Answer 1

Correct option is (b) Na₂CdCl₂

The outer shell electronic configuration of Cu²⁺ has 3d⁹ configuration and contain 1 unpaired electron, thus it is coloured.

Na₂[CdCl₂], compound is not coloured because of central atom Cd which has 4d¹⁰5s² electronic configuration so transition do not occur.