When we consider an inert electrode in a cell; which statement is not suitable for it?
(A) It provides surface either for oxidation or for reduction reaction.
(B) It does not participate in the cell reaction.
(C) It provides surface for redox reaction.
(D) It provides surface for conduction of electrons.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Only (C)
Some half-cells have no metal of their own that can act as the electrode, for example the hydrogen electrode or a solution of \( \ce{Fe^3+} \) and \( \ce{Fe^2+} \) ions. An inert electrode such as platinum or gold is then dipped into the solution. It does not take part in the reaction; it only provides a surface on which the half-reaction takes place and through which the electrons enter or leave the external circuit. For example, in the standard hydrogen electrode:
\( \displaystyle \ce{H2(g) -> 2H+(aq) + 2e^-} \quad (\text{on the Pt surface}) \)
An electrode is either the anode, where only oxidation takes place, or the cathode, where only reduction takes place. One electrode never carries the complete redox reaction.
(A) It provides surface either for oxidation or for reduction reaction. — Correct. Depending on whether it is the anode or the cathode, the inert electrode carries the oxidation half or the reduction half.
(B) It does not participate in the cell reaction. — Correct. Platinum is not oxidised or reduced; it appears in neither half-reaction.
(C) It provides surface for redox reaction. — Incorrect. A redox reaction means oxidation and reduction together, and these take place at two different electrodes. A single inert electrode provides the surface for only one half-reaction.
(D) It provides surface for conduction of electrons. — Correct. The electrons released or taken up in the half-reaction pass through the metal to the external circuit.
NCERT (2026-27 edition):
Measurement of Electrode Potential – …
