What will happen during the electrolysis of aqueous solution of \(CuSO_4\) by using platinum electrodes?
- Copper will deposit at cathode
- Copper will deposit at anode
- Oxygen will be released at anode
- Oxygen will be released at cathode
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → A and C
Platinum electrodes are inert: they do not take part in the reaction, so the products come from the ions and water in the solution.
(A) Copper will deposit at cathode — Correct. \( \ce{Cu^{2+}} \) is reduced more easily than water: \( \ce{Cu^{2+}} \) + 2e− → Cu.
(B) Copper will deposit at anode — Incorrect. The anode is where oxidation takes place; \( \ce{Cu^{2+}} \) ions are reduced only at the cathode.
(C) Oxygen will be released at anode — Correct. \( \ce{SO4^{2-}} \) is not oxidised, so water is oxidised: \( \ce{2H2O} \) → \( \ce{O2} \) + \( \ce{4H^{+}} \) + 4e−.
(D) Oxygen will be released at cathode — Incorrect. Oxygen comes from the oxidation of water, and oxidation takes place only at the anode; at the cathode \( \ce{Cu^{2+}} \) is reduced to copper.
NCERT (2026-27 edition):
Products of Electrolysis – “Products of electrolysis depend on the nature of material being electrolysed and the type of electrodes being used. If the electrode is inert (e.g., platinum or gold), it does not participate in the chemical reaction and acts only as source or sink for electrons. On the other hand, if the electrode is reactive, it participates in the electrode reaction.”
Note: The same/similar question has been asked in different years by NTA as per the details given below:
| 2026 | 2025 | 2024 | 2023 | 2022 |
|---|---|---|---|---|
| – | – | – | 08-06 S3 31-05 S2 | – |