The emf of the cell Zn|Zn2+(aq)||Cu2+(aq)|Cu is independent of which…

The correct answer is Option (1) → The volumes of the ZnSO₄ and CuSO₄ solutions taken (at fixed concentrations)

For the Daniell cell, \( \ce{Zn(s) + Cu^2+(aq) -> Zn^2+(aq) + Cu(s)} \) (n = 2), the Nernst equation gives:

    \( \displaystyle E_{(cell)}=E^{\circ}_{(cell)}-\frac{2.303RT}{2F}\log\frac{[\ce{Zn^2+}]}{[\ce{Cu^2+}]} \)

The emf depends only on the concentrations and the temperature. E_(cell) is an intensive parameter: it does not depend on how much of each solution is taken.

Option (1) The volumes of the ZnSO₄ and CuSO₄ solutions taken (at fixed concentrations) — The emf is independent of it. Volume does not appear in the Nernst equation; a larger volume at the same concentration changes only how long the cell can run, not its emf.

Option (2) Concentration of Cu²⁺ — The emf depends on it. [\( \ce{Cu^2+} \)] is in the denominator of the log term, so the emf rises as [\( \ce{Cu^2+} \)] increases.

Option (3) Concentration of Zn²⁺ — The emf depends on it. [\( \ce{Zn^2+} \)] is in the numerator, so the emf falls as [\( \ce{Zn^2+} \)] increases.

Option (4) Temperature — The emf depends on it. T appears in the term 2.303RT/2F, so the emf changes with temperature.

NCERT (2026-27 edition):
2.3.2 Electrochemical Cell and Gibbs Energy of the Reaction – “… It may be remembered that E_(cell) is an intensive parameter but Δ_rG is an extensive thermodynamic property and the value depends on n.”