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COMEDK202510 May 2025Evening ShiftChemistryd and f Block ElementsActual

Arrange the following ions in the decreasing order of total covalent double bonds formed by the transition metal(s) with oxygen. A. = chromate B. = permanganate C. = dichromate

Options

  1. AB > C > A
  2. BA > B > C
  3. CB > A > C
  4. DC > B > A

Correct answer

D. C > B > A

Step-by-step solution

Chromate ( CrO₄²⁻ ): Cr is in +6 state, bonded to 4 oxygens. Structure has 2 double bonds ( Cr=O ) and 2 single bonds ( Cr-O^- ). Total = 2 Permanganate ( MnO₄^- ): Mn is in +7 state, bonded to 4 oxygens. Structure has 3 double bonds ( Mn=O ) and 1 single bond ( Mn-O^- ). Total = 3 Dichromate ( Cr₂O₇²⁻ ): Two Cr atoms linked by a bridging oxygen. Each Cr has 2 double bonds ( Cr=O ). Total = 2 2 = 4 Decreasing order: C > B > A (Dichromate > Permanganate > Chromate)

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