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COMEDK2021Chemistryd and f Block Elements

The oxidation number of Cr in CrO ₅ which has the following structure, is

Options

  1. A+4
  2. B+5
  3. C+3
  4. D+6

Correct answer

D. +6

Step-by-step solution

The structure of CrO ₅ is a butterfly structure where the central chromium atom is bonded to one oxygen atom via a double bond and to four oxygen atoms via two peroxo linkages. In the peroxo linkage, the oxidation state of each oxygen atom is -1 . Let the oxidation number of Cr be x . The molecule contains one oxo group (O ²⁻ ) and two peroxo groups (O₂²⁻ ). The sum of oxidation states in a neutral molecule is zero: x + 1(-2) + 2(-2) = 0 x - 2 - 4 = 0 x = +6 Answer: +6

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