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NDA 2020 GAT · General Knowledge · Chemical Reactions · medium

The oxidation state of chromium in potassium dichromate, K2Cr2O7, is

Single correct option

The oxidation state of chromium in potassium dichromate, K2Cr2O7, is
  1. A. +3
  2. B. +6
  3. C. +7
  4. D. +12
Show answer and solution

Answer: (B) +6

Potassium is +1 (two atoms give +2) and oxygen is -2 (seven atoms give -14). Therefore 2 + 2x - 14 = 0, giving x = +6. The value +12 is the total for two chromium atoms and not the oxidation state of one atom, which is the trap.
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Original question written in the NDA 2020 GAT pattern and checked twice for the correct answer. Not an official question paper. How we write and check questions · Corrections policy · Report a mistake