Asked in PMC Practice Test 12 (2021) 2021Moderate

The oxidation number of Mn in (MnO4)- is:

Correct answer: A. 7

  • A. 7
  • B. -7
  • C. 6
  • D. -6

Explanation

The oxidation number of Mn in MnO4- can be calculated by considering the overall charge of the compound and assigning oxidation numbers to the other elements. Let x be the oxidation number of Mn in MnO4-. The total charge of the compound is -1, so we can set up the equation: x + 4(-2) = -1 Simplifying the equation: x - 8 = -1 x = -1 + 8 x = +7 Therefore, the oxidation number of Mn in MnO4- is +7.

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About Oxidation and Reduction

Oxidation involves loss of electrons, increase in oxidation number or addition of oxygen, while reduction involves electron gain, decrease in oxidation number or removal of oxygen. The topic covers oxidising and reducing agents, oxidation-number changes, redox equations and the distinction between oxidation at the anode and reduction at the cathode.

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