Question

Simplified absorption spectra of three complexes ((i) and (ii) and (iii)) of M⁺ⁿ ion are provided below; their λ_max values are marked as A, B and C respectively. The correct match between the complexes and their λ_max values is:

(i) [M(NCS)₆]^{(–6 + n)}

(ii) [MF₆]^{(–6 + n)}

(iii) [M(NH₃)₆]ⁿ⁺

(1) A-(i), (B)-(ii), C-(iii) 

(2) A-(ii), (B)-(iii), C-(i)

(3) A-(ii), (B)-(i), C-(iii) 

(4) A-(iii), (B)-(i), C-(ii)

Answer 1

Ans. (4) A-(iii), (B)-(i), C-(ii)

Sol. Stronger the ligand greater is splitting of d orbitals and smaller will be wave length of light absorbed.

The splitting power of ligands is NH₃ > NCS^– > F^–

So order of wave length of light absorbed is $\lambda_{NH_3}<\lambda_{NCS^-}<\lambda_{F^-}$