Q24 / 160 · AP EAMCET 2023 (18 May Shift 1) · Chemistry

Some statements about Lechlanche cell are (I) Anode is zinc metal (II) Cathode is graphite rod surrounded by powdered $\mathrm{MnO}_2$ and carbon (III)Electrolyte is a moist paste of $\mathrm{ZnO}$ and $\mathrm{KOH}$ (IV)Oxidation product is $\mathrm{ZnO}$ The correct statements are

  • Correct answer
    A
    I \& II only
  • B
    II \& III only
  • C
    I \& IV only
  • D
    I, II \& III only

Solution

Lechlunche cell:- Anode : $\mathrm{Zn}$ Container $\mathrm{Zn}(\mathrm{s}) \rightarrow \mathrm{Zn}^{2+}$ (aq.) $+2 \mathrm{e}^{-}$ Cathode: Carbon (graphite) $+\mathrm{MnO}_2+$ Carbon powder. $\mathrm{MnO}_2+\mathrm{NH}_4^{+}+\mathrm{e}^{-} \rightarrow \mathrm{MnO}(\mathrm{OH})+\mathrm{NH}_3$ Electrolyte $=\mathrm{NH}_4 \mathrm{Cl}+\mathrm{ZnCl}_2$ paste Thus, I and II are correct.

Hence, the correct answer is option: 'A'.

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