Question

Amongst the following the compound that is both paramagnetic and coloured is

(a) K₂Cr₂O₇

(b) (NH₄)₂ [TiCl₆]

(c) CoSO₄

(d) K₃[Cu(CN)₄]

Answer 1

Correct option  (c) CoSO₄ 

Explanation:

In (NH₄)₂ [(TiCl₆)], Ti⁴⁺ (3d⁰ 4s⁰ ) has no unpaired electrons.

In K₂Cr₂O₇ , Cr⁶⁺ (3p⁶ d⁰ ) has no unpaired electrons. In CoSO₄ , Co²⁺ (d⁷ ) has unpaired electrons in d-orbitals, so it is both paramagnetic and coloured.

In K₃ [Cu(CN)₄], Cu⁺ (3d¹⁰), has no unpaired electron.