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JAMB Chemistry 1999 Question 18

Question 18

Redox Reactions

The correct order of increasing oxidation number of the transition metal ions for the compounds K2Cr2O7, V2O5 and KMnO4 is

  1. A.V2O5 < K2Cr2O7 < KMnO4
  2. B.K2Cr2O7 < KMnO4 < V2O5
  3. C.KMnO4 < K2Cr2O7 < V2O5
  4. D.KMnO4 < V2O5 < K2Cr2O7.
Show the answer and explanation

Answer: A (V2O5 < K2Cr2O7 < KMnO4)

Explanation

V in V2O5 is +5, Cr in K2Cr2O7 is +6 and Mn in KMnO4 is +7, so the order is V2O5 < K2Cr2O7 < KMnO4.