Key Fact
Galvanic vs electrolytic cells
Galvanic (voltaic): chemical → electrical energy (spontaneous, ΔG<0). Electrolytic: electrical → chemical (non-spontaneous, ΔG>0; external EMF needed).
-- NCERT Class 12 Chemistry, Ch. 2, p. 31Electrochemical Cells
8 MCQs2 revision cards9-step worked example
Source: NCERT Redox Reactions and ElectrochemistryPYQ coverage: NEET 2020, 2024Official key: NTA-verifiedLast updated: 27 Sep 2026
Electrochemical Cells, explained for NEET
An electrochemical cell converts chemical energy into electrical energy (galvanic cell) or uses electrical energy to drive a non-spontaneous reaction (electrolytic cell). NEET questions on this topic test whether you can distinguish the two types and correctly assign electrode polarity, electrode names, and the sign convention for cell EMF.
The trap that costs marks: confusing which electrode is the anode and which is the cathode across galvanic and electrolytic cells. In a galvanic cell, oxidation occurs at the anode (negative terminal); in an electrolytic cell, oxidation still occurs at the anode, but the anode is now the positive terminal (connected to the positive terminal of the external battery). The chemistry definition — anode = oxidation, cathode = reduction — never changes. The polarity does.
Galvanic (voltaic) cell. Two half-cells connected by a salt bridge. Oxidation at the anode releases electrons that flow through the external circuit to the cathode, where reduction occurs. The salt bridge maintains electrical neutrality by allowing ion migration. Cell representation uses the convention: anode on the left, cathode on the right, single vertical line for phase boundary, double vertical line for the salt bridge.
Example: the Daniell cell — Zn(s) | Zn²⁺(aq) || Cu²⁺(aq) | Cu(s). Zinc is oxidised (anode, negative terminal); copper ions are reduced (cathode, positive terminal).
Standard cell EMF is calculated as E°_cell = E°_cathode − E°_anode, using standard reduction potentials for both electrodes (NCERT Class 12 Chemistry Chapter 2, page 34). A positive E°_cell means the cell reaction is spontaneous under standard conditions.
Electrolytic cell. A single container with two electrodes dipped in an electrolyte, driven by an external power source. The external battery forces electrons to flow in the non-spontaneous direction. Anode (positive, connected to + terminal) undergoes oxidation; cathode (negative, connected to − terminal) undergoes reduction.
Watch-out: when NEET gives you a cell diagram without labelling which type it is, check for a salt bridge (galvanic) versus an external battery (electrolytic) before assigning terminal polarity.
Can you answer these Electrochemical Cells MCQs?
Select an option to see the explanation. Wrong answers show why your choice was tempting — and name the exact trap it exploits.
MCQ 1Easy RecallPractice
In any electrochemical cell, oxidation always occurs at the:
Show answer and why every option is right or wrong
Answer: A. By definition, the anode is the electrode where oxidation occurs, regardless of whether the cell is galvanic or electrolytic (NCERT Class 12 Chemistry Chapter 2, page 34).
Why B is wrong: B — The cathode is the site of reduction, not oxidation. Confusing these two is a common polarity error.
Why C is wrong: C — The positive terminal is the cathode in a galvanic cell but the anode in an electrolytic cell. 'Positive terminal' does not universally identify the oxidation electrode.
Why D is wrong: D — The salt bridge allows ion flow to maintain electrical neutrality; no electrode reaction occurs there.
MCQ 2Easy RecallPractice
Which component in a galvanic cell maintains electrical neutrality of the solutions in the two half-cells?
Show answer and why every option is right or wrong
Answer: C. The salt bridge allows migration of ions between the two half-cell solutions, preventing charge buildup and maintaining electrical neutrality (NCERT Class 12 Chemistry Chapter 2, page 34).
Why A is wrong: A — The external wire carries electrons between electrodes but does not balance ionic charges in solution.
Why B is wrong: B — The voltmeter measures potential difference; it does not participate in maintaining solution neutrality.
Why D is wrong: D — The electrode surface is where the redox half-reaction occurs; it does not balance the ionic charges in the bulk solution.
MCQ 3Easy RecallPractice
In an electrolytic cell, the anode is connected to the:
Show answer and why every option is right or wrong
Answer: A. In an electrolytic cell, the external battery forces the anode to be positive (connected to the + terminal), where oxidation is driven. This is opposite to the galvanic cell, where the anode is the negative terminal (NCERT Class 12 Chemistry Chapter 2).
Why B is wrong: B — The negative terminal of the battery connects to the cathode in an electrolytic cell. Swapping anode/cathode terminal polarity between galvanic and electrolytic cells is a high-frequency confusion.
Why C is wrong: C — Electrolytic cells typically use a single container; they do not require a salt bridge. This is a feature of galvanic cells.
Why D is wrong: D — The anode and cathode are two distinct electrodes. Saying the anode connects to the cathode conflates the two.
MCQ 4Concept TrapPractice
In a Daniell cell, the main function of the salt bridge is to:
Show answer and why every option is right or wrong
Answer: B. B is correct. As the cell works, Zn²⁺ ions accumulate in the anode compartment and Cu²⁺ ions are removed from the cathode compartment. Ions from the salt bridge (for example K⁺ and Cl⁻) migrate into the two compartments to balance these charges. Without it the charge imbalance would stop the reaction almost at once.
Why A is wrong: A is wrong because electrons never pass through the solutions or the salt bridge. They travel through the external wire, from the zinc anode to the copper cathode.
Why C is wrong: C is wrong because the Cu²⁺ ions come from the copper sulphate solution in the cathode compartment. The salt bridge contains an inert electrolyte such as KCl or KNO₃.
Why D is wrong: D is wrong because oxidation takes place at the anode, the zinc electrode. The salt bridge takes no part in the electrode reactions.
MCQ 5Direct ApplicationPractice
In the cell notation Ag(s) | Ag⁺(aq) || Cu²⁺(aq) | Cu(s), which species is being oxidised?
Show answer and why every option is right or wrong
Answer: D. In standard cell notation, the species on the left side of the double vertical line is the anode half-cell. Ag(s) is oxidised to Ag⁺(aq) at the anode (NCERT Class 12 Chemistry Chapter 2).
Why A is wrong: A — Cu(s) appears on the right (cathode side) as the product of reduction (Cu²⁺ gaining electrons), not as a species being oxidised.
Why B is wrong: B — Ag⁺(aq) is the oxidised form of silver, already in solution. The species being oxidised is Ag(s), which loses electrons to form Ag⁺.
Why C is wrong: C — Cu²⁺(aq) is the species being reduced (gaining electrons to form Cu). It sits in the cathode compartment.
MCQ 6Direct ApplicationPractice
A student sets up a galvanic cell and an electrolytic cell side by side. In the galvanic cell, the anode carries a ______ charge; in the electrolytic cell, the anode carries a ______ charge.
Show answer and why every option is right or wrong
Answer: B. In a galvanic cell, electrons leave the anode spontaneously, making it the negative terminal. In an electrolytic cell, the external battery forces the anode to be positive. The definition of anode (oxidation electrode) is the same in both, but the terminal sign flips (NCERT Class 12 Chemistry Chapter 2).
Why A is wrong: A — This would mean the anode is positive in both cells. The galvanic cell anode is negative because electrons flow away from it spontaneously.
Why C is wrong: C — This would mean the anode is negative in both cells. The electrolytic cell anode is connected to the positive terminal of the battery.
Why D is wrong: D — This is the exact reverse of the correct answer. The galvanic anode is negative, not positive.
MCQ 7Direct ApplicationPractice
If the standard cell EMF for a proposed galvanic cell comes out to be −0.15 V, what does this indicate?
Show answer and why every option is right or wrong
Answer: C. A negative E°_cell means the forward reaction (as written in the cell notation) is non-spontaneous. The reverse reaction would be spontaneous. This is a direct consequence of E°_cell = E°_cathode − E°_anode (NCERT Class 12 Chemistry Chapter 2, page 34).
Why A is wrong: A — A negative EMF does not produce useful work in the forward direction. The cell as written would require an external power source (electrolytic operation) to proceed.
Why B is wrong: B — The salt bridge has no bearing on the sign of E°_cell. A negative value is a thermodynamic result, not an equipment fault.
Why D is wrong: D — The '°' in E°_cell denotes standard conditions (1 M, 1 bar, 298 K). A negative value under standard conditions simply means the reaction is non-spontaneous as written.
MCQ 8Concept TrapPractice
A student argues that in an electrolytic cell, the cathode is where oxidation occurs because the cathode is connected to the negative terminal. Which part of this reasoning is incorrect?
Show answer and why every option is right or wrong
Answer: D. In an electrolytic cell, the cathode IS connected to the negative terminal of the battery — that part is correct. The error is in claiming oxidation occurs there. By definition, reduction always occurs at the cathode, regardless of cell type (NCERT Class 12 Chemistry Chapter 2).
Why A is wrong: A — The cathode IS connected to the negative terminal of the external battery in an electrolytic cell. This option incorrectly disputes a correct fact.
Why B is wrong: B — Oxidation never occurs at the cathode in any electrochemical cell. The cathode is defined as the electrode where reduction occurs.
Why C is wrong: C — The terminal assignment (cathode = negative in electrolytic cell) is correct. Only the reaction type claim is wrong, not both.
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Electrochemical Cells: quick recall before you leave
How do you solve a Electrochemical Cells question? A worked example
- 1
Given
A galvanic cell is constructed with the following half-cells:• Fe(s) | Fe²⁺(1 M) — E°(Fe²⁺/Fe) = −0.44 V• Ag⁺(1 M) | Ag(s) — E°(Ag⁺/Ag) = +0.80 V
- 2
Required
(a) Write the cell notation. (b) Calculate E°_cell. (c) Identify the direction of electron flow.
- 3
Concept
In a galvanic cell, the electrode with the lower (more negative) reduction potential acts as the anode (oxidation). The electrode with the higher reduction potential acts as the cathode (reduction). Cell notation: anode on the left, cathode on the right.
- 4
Formula
E°_cell = E°_cathode − E°_anode
- 5
Substitution
E°_cathode = E°(Ag⁺/Ag) = +0.80 V
E°_anode = E°(Fe²⁺/Fe) = −0.44 V
E°_cell = (+0.80) − (−0.44) - 6
Calculation
E°_cell = 0.80 + 0.44 = +1.24 V
Note: the reduction potential values (−0.44 V and +0.80 V) are exact standard table values used as given data. They do not introduce significant-figure considerations. - 7
Final answer
(a) Cell notation: Fe(s) | Fe²⁺(1 M) || Ag⁺(1 M) | Ag(s)
(b) E°_cell = +1.24 V
(c) Electrons flow from the iron electrode (anode) through the external circuit to the silver electrode (cathode).
Since E°_cell > 0, the cell reaction is spontaneous under standard conditions. - 8
Common trap
Subtracting in the wrong direction: E°_anode − E°_cathode = (−0.44) − (0.80) = −1.24 V. A negative result would falsely suggest the reaction is non-spontaneous. Always compute cathode minus anode.
- 9
Similar NEET-style question
Given E°(Ni²⁺/Ni) = −0.25 V and E°(Cu²⁺/Cu) = +0.34 V, construct the cell notation for a spontaneous galvanic cell and calculate E°_cell.
Answer: Ni(s) | Ni²⁺(1 M) || Cu²⁺(1 M) | Cu(s); E°_cell = +0.34 − (−0.25) = +0.59 V.
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What to remember before solving Electrochemical Cells questions
More in Redox Reactions and Electrochemistry: 4 exam traps and mistakes · 5 formulas · 2 question patterns from its other lessons.
Electrochemical Cells questions from past NEET papers
4 questions from NEET 2020, 2024. Answers verified against NTA official keys.
NEET 2024Revised key
1A-II, B-IV, C-I, D-III
2A-III, B-IV, C-I, D-II
3A-II, B-III, C-I, D-IV
4A-III, B-IV, C-II, D-I
NTA Answer: Option 1(revised_final)
NEET 2024Revised key
13.15 g
20.315 g
331.5 g
40.0315 g
NTA Answer: Option 2(revised_final)
NEET 2020
14
21
32
43
NTA Answer: Option 2(final)
NEET 2020
1SO2 gas
2Hydrogen gas
3Oxygen gas
4H2S gas
NTA Answer: Option 3(final)
All 21 past-paper questions from Redox Reactions and Electrochemistry →
Sources
NCERT refs: Class 12 Chemistry Chapter 2, p.34
Page numbers are the ones printed in the current NCERT textbook (2023 rationalised edition), unless marked pre-2023. The books are free at ncert.nic.in.
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