The standard reduction potentials for Zn^2+/Zn , Ni^2+/Ni , and Fe^2+/Fe are -0.76 , -0.23 and -0.44 V respectively. The reaction X + Y^2+ → X^2+ + Y - Chemistry MCQ AIEEE 2012 2026 | ExamTest.live

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The standard reduction potentials for Zn^{2 +} / Zn, Ni^{2 +} / Ni, and Fe^{2 +} / Fe are - 0.76, - 0.23 and - 0.44 V respectively. The reaction X + Y^{2 +} \to X^{2 +} + Y will be spontaneous when:

Solution & Step-by-step Explanation

For a reaction to be spontaneous, E_{cell}^{\circ} must be positive. E_{cell}^{\circ} = E_{cathode}^{\circ} - E_{anode}^{\circ} = E_{reduction}^{\circ} - E_{oxidation}^{\circ} .Here X is oxidized and Y^{2 +} is reduced. E_{cell}^{\circ} = E^{\circ} (Y^{2 +} / Y) - E^{\circ} (X^{2 +} / X) .For option D: X = Zn, Y = Ni . E_{cell}^{\circ} = (- 0.23) - (- 0.76) = + 0.53 V . (Spontaneous)Checking others:A: (- 0.44) - (- 0.23) = - 0.21 V (Non-spontaneous)B: (- 0.76) - (- 0.23) = - 0.53 V (Non-spontaneous)C: (- 0.76) - (- 0.44) = - 0.32 V (Non-spontaneous)

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The standard reduction potentials for Zn^{2 +} / Zn, Ni^{2 +} / Ni, and Fe^{2 +} / Fe are - 0.76, - 0.23 and - 0.44 V respectively. The reaction X + Y^{2 +} \to X^{2 +} + Y will be spontaneous when:

X = Ni, Y = Fe

X = Ni, Y = Zn

X = Fe, Y = Zn

X = Zn, Y = Ni

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