What is the oxidation number of Cr in K₂Cr₂O₇?
Answer and explanation
Correct answer: D. +6
- Step 1: The oxidation numbers in a neutral compound add up to zero (H is +1, O is −2). Step 2. Solving for Cr gives +6. Answer: +6. Why not the others: +3 is what you get if you miscount the oxidation numbers of the other atoms. +7 is what you get if you miscount the oxidation numbers of the other atoms. +12 is what you get if you miscount the oxidation numbers of the other atoms.
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