Question

Compound that is both paramagnetic and coloured is

• A. K2Cr2O7
• B. (NH4)2 [TiCl6]
• C. VOSO4
• D. K3[Cu(CN)4]

Answer 1

Answer: (D)

K3$Cu(CN)4$

Answer 2

(1) Valence shell electron configuration of Cu+ is [Ar]18 3d10 ; so n = 0

(2) Valence shell electron configuration of Zn2+ is [Ar]18 3d10 ; so n = 0

(3) Valence shell electron configuration of Sc3+ is [Ar]18 3d0 ; so n = 0

(4) Valence shell electron configuration of V4+ is [Ar]18 3d1 ; so n = 1

As V4+ has one unpaired electron and so in presence of water as ligand it will undergo d-d transition of electron. Hence V4+ ions will produce colour in the solution.