The standard electrode potential for the Daniell cell is 1.1 V. The s…

The correct answer is Option (1) → –212.3 kJ/mol

A galvanic cell does electrical work at the cost of the reaction’s Gibbs energy. For n moles of electrons passing through a cell of standard emf E°_cell:

    \( \displaystyle \Delta_rG^{\circ}=-nFE^{\circ}_{cell} \)

A positive E°_cell gives a negative ΔG°, which means the cell reaction is spontaneous.

For the Daniell cell:

    \( \displaystyle \ce{Zn(s) + Cu^2+(aq) -> Zn^2+(aq) + Cu(s)} \)

• Anode: \( \ce{Zn(s) -> Zn^2+(aq) + 2e^-} \); cathode: \( \ce{Cu^2+(aq) + 2e^- -> Cu(s)} \); so n = 2.

• E°_cell = E°_cathode − E°_anode = 0.34 − (−0.76) = 1.10 V.

    \( \displaystyle \Delta_rG^{\circ}=-2\times96500\ \mathrm{C\,mol^{-1}}\times1.10\ \mathrm{V} \)

    \( \displaystyle \Delta_rG^{\circ}=-212300\ \mathrm{J\,mol^{-1}} \)

    \( \displaystyle \Delta_rG^{\circ}=-212.3\ \mathrm{kJ\,mol^{-1}} \)

Shortcut: 2 × 96500 × 1.1 ≈ 212000 J, which is about 212 kJ. Only Options (1) and (2) show 212.3, and only Option (1) has it in kJ/mol.

Note 1: In the book’s working (extract below), the value in joules is printed as −21227 J mol⁻¹; it should be −212270 J mol⁻¹, which is the −212.27 kJ mol⁻¹ given on the next line.

Note 2: This question is from NCERT (2026-27). NTA sets numerical questions from NCERT too, so do not ignore NCERT while practising numericals.

NCERT (2026-27 edition):
Electrochemical Cell and Gibbs Energy of the Reaction – …

Note 3: The same/similar question has been asked in different years by NTA as per the details given below: