Verified Solution • 2025–26 Session moderate

QJEEM24Ch262e: JEE Main 2024 Chemistry - Class 12 JEEM24Ch262e Solution: Given below are two statements : Statement (I) : Fusion of with …

Given below are two statements :

Statement (I) : Fusion of MnO2\mathrm{MnO}_2 with KOH\mathrm{KOH} and an oxidising agent gives dark green K2MnO4\mathrm{K}_2 \mathrm{MnO}_4 .

Statement (II) : Manganate ion on electrolytic oxidation in alkaline medium gives permanganate ion.

In the light of the above statements, choose the correct answer from the options given below :

Multiple Choice Options

  • A Statement I is false but Statement II is true
  • B Statement I is true but Statement II is false
  • C Both Statement I and Statement II are false
  • D Both Statement I and Statement II are true

Step-by-Step Verified Solution

Statement I is indeed true. When MnO2\mathrm{MnO}_2 (manganese dioxide) is fused with KOH\mathrm{KOH} (potassium hydroxide) and an oxidising agent such as KNO3\mathrm{KNO}_3 (potassium nitrate), it forms dark green potassium manganate ( K2MnO4\mathrm{K}_2\mathrm{MnO}_4 ). The reaction can be represented as follows:

2MnO2+4KOH+O2→2K2MnO4+2H2O\mathrm{2MnO}_2 + 4KOH + \mathrm{O}_2 \rightarrow \mathrm{2K}_2\mathrm{MnO}_4 + 2H_2\mathrm{O}

This process involves the oxidation of manganese dioxide to manganate ion ( MnO42−\mathrm{MnO}_4^{2-} ) in an alkaline medium.

Statement II is also true. The manganate ion ( MnO42−\mathrm{MnO}_4^{2-} ), when subjected to electrolytic oxidation in an alkaline medium, can indeed be converted into permanganate ion ( MnO4−\mathrm{MnO}_4^- ), which is characterized by a deep purple color. This conversion is an example of an electron-loss (oxidation) process at the anode of an electrolytic cell. The reaction can be represented as follows:

MnO42−+H2O→MnO4−+2OH−+2e−\mathrm{MnO}_4^{2-} + \mathrm{H}_2\mathrm{O} \rightarrow \mathrm{MnO}_4^- + 2\mathrm{OH}^- + 2e^-

Thus, both statements I and II are accurate, making the correct answer:

Option D: Both Statement I and Statement II are true.

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