Electrochemistry
A galvanic cell is an electrochemical cell that converts the chemical energy of a spontaneous redox reaction into electrical energy whereas, an electrolytic cell is a device which uses electrical energy to carry out the non-spontaneous chemical reactions. We can construct innumerable number of galvanic cells on the pattern of Daniell cell (Cu-Zn cell) by taking combinations of different half-cells. Each half-cell consists of a metallic electrode dipped into an electrolyte. The two half-cells are connected by a metallic wire through a voltmeter and a switch externally. The electrolytes of the two half-cells are connected internally through a salt bridge. In a galvanic cell, the half-cell in which oxidation takes place is called anode and it has a negative potential with respect to the solution and in an accepted convention we keep the anode on the left and the cathode on the right side. The potential difference between the two electrodes of a galvanic cell is called the cell potential and is measured in volts. The cell potential is the difference between the electrode potentials (reduction potentials) of the cathode and anode. It is called the cell electromotive force (emf) of the cell when no current is drawn through the cell.
In which of the following cells, electrical energy can be used to carry out chemical reactions that do not proceed spontaneously?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Electrolytic cell
A galvanic cell uses a spontaneous redox reaction to produce electrical energy. An electrolytic cell does the reverse: an external source of electrical energy drives a non-spontaneous reaction, as in electrolysis.
Why the other options are incorrect
Option (1) Galvanic cell — Incorrect. It runs a spontaneous reaction and produces electricity; it does not consume it.
Option (2) Daniell cell — Incorrect. It is a galvanic cell (Zn | \( \ce{Zn^{2+}} \) || \( \ce{Cu^{2+}} \) | Cu).
Option (4) Cu-Zn cell — Incorrect. This is another name for the Daniell cell, also galvanic.
NCERT (2026-27 edition):
Electrochemical Cells – …

