Q9 / 60 · JEE Advanced 2011 (Paper 2) · Chemistry

Reduction of the metal centre in aqueous permanganate ion involves

  • Correct answer
    A
    three electrons in neutral medium
  • B
    five electrons in neutral medium
  • Correct answer
    C
    three electrons in alkaline medium
  • Correct answer
    D
    five electrons in acidic medium

Solution

In neutral medium: $\quad \mathrm{MnO}_4^{-} \rightarrow \mathrm{MnO}_2\left(\mathrm{Mn}^{7+}+3 e^{-} \rightarrow \mathrm{Mn}^{4+}\right)$ In alkaline medium : $\quad \mathrm{MnO}_4^{-} \rightarrow \mathrm{MnO}_2\left(\mathrm{Mn}^{7+}+3 \varepsilon^{-} \rightarrow \mathrm{Mn}^{4+}\right)$ In acidic medium : $\quad \mathrm{Mn}_4^{-} \rightarrow \mathrm{Mn}^{2+}\left(\mathrm{Mn}^{7+}+5 e^{-} \rightarrow \mathrm{Mn}^{2+}\right)$

Hence, the correct answer is options: 'A', 'C', 'D'.

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