Q16 / 90 · JEE Main 2024 (05 Apr Shift 2) · Chemistry

For the electro chemical cell \(\begin{gathered} \text { If } \mathrm{E}_{\left(\mathrm{M}^{2+} / \mathrm{M}\right)}^0=0.46 \mathrm{~V} \text { and } \mathrm{E}_{\left(\mathrm{x} / \mathrm{X}^{2-}\right)}^0=0.34 \mathrm{~V} \text {. } \end{gathered}\) Which of the following is correct?

  • A
    \(\mathrm{M}+\mathrm{X} \rightarrow \mathrm{M}^{2+}+\mathrm{X}^{2-}\) is a spontaneous reaction
  • B
    \(\mathrm{E}_{\text {cell }}=0.80 \mathrm{~V}\)
  • C
    \(\mathrm{E}_{\text {cell }}=-0.80 \mathrm{~V}\)
  • Correct answer
    D
    \(\mathrm{M}^{2+}+\mathrm{X}^{2-} \rightarrow \mathrm{M}+\mathrm{X}\) is a spontaneous reaction

Solution

$\begin{aligned} & \mathrm{M} \mid \mathrm{M}^{+2} \| \mathrm{X} / \mathrm{X}^{2-} \\ & \mathrm{E}_{\mathrm{cell}}^{\mathrm{o}}=\mathrm{E}_{\mathrm{M} / \mathrm{M}^{+2}}^{\mathrm{o}}+\mathrm{E}_{\mathrm{X} / \mathrm{X}^{-2}}^{\mathrm{o}} \\ & =-0.46+0.34=-0.12 \mathrm{~V} \end{aligned}$
As $\mathrm{E}_{\text {cell }}^{\mathrm{o}}$ is negative so anode becomes cathode and cathode become anode. Spontaneous reaction will be $\mathrm{M}^{+2}+\mathrm{X}^{2-} \longrightarrow \mathrm{M}+\mathrm{X}$

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

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