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JAMB Chemistry 1991 Question 25

Question 25

Redox Reactions

MnO4− + 8H+ + ne → Mn2+ + 4H2O. Which is the value of n in the reaction above?

  1. A.2
  2. B.3
  3. C.4
  4. D.5
Show the answer and explanation

Answer: D (5)

Explanation

Manganese goes from +7 in MnO4− to +2, so it gains 5 electrons. Charges check: −1 + 8 − 5 = +2.