Chemistry · Colour and magnetic properties

The incorrect statement(s) among the following is (are): ¡) Primary valency of a

The incorrect statement(s) among the following is (are): ¡) Primary valency of a transition metal ion in complex represent its oxidation number. ii) \( Z n^{2+} \) is colourless. iii) \( M n C l_{2} \) exhibits green color in aqueous solution. iv) \( F e, C o, N i \) complexes are diamagnetic in nature.

  • A. i and ii
  • B. ii only
  • C. iii and iv
  • D. iv only

Step-by-step solution

Statement i is correct: primary valency corresponds to oxidation number. Statement ii is correct: Zn2+ has d10 configuration, hence no d-d transitions and colourless. Statement iii is incorrect: MnCl2 in aqueous solution is pale pink, not green. Statement iv is incorrect: Fe, Co, Ni complexes can be paramagnetic depending on oxidation state and ligands (e.g., Fe3+ is paramagnetic). Thus, incorrect statements are iii and iv.
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