What the board asks
We went through the ISC board papers, question by question, and matched each question to a topic. Here is what was asked, how often, and what was never asked.
Chemistry: 384 topics in the 2027 syllabus, across 10 units. The board has asked 252 of them at least once. 132 were never asked in the papers we checked.
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C2 Electrochemistry
All the topics in Chemistry: Electrochemistry
Asked topics first, the most asked at the top. Tap a topic to see what to write, the result, the years, and the real board questions.
40 topics shown
| # | Topic | Type | Marks | Times asked | Last asked | Status |
|---|---|---|---|---|---|---|
| 1 | Faraday's first law: mass, charge, current or timeWrite the electrode reaction to get n, find Q = It, then m = MQ/(nF), or rearrange for Q, I, t or the atomic mass; give units and convert minutes to seconds. | Numericals | 2 | 7 papers | Specimen 2027 | Asked |
| 2 | Gibbs energy and maximum work from cell emfFind n from the balanced cell reaction, compute delta G0 = -nFE0cell (or delta G = -nFEcell at given concentrations) in J and kJ mol-1, and state spontaneity or the maximum electrical work. | Numericals | 2 | 6 papers | 2026 | Asked |
| 3 | Nernst equation: emf of a cell at given concentrationsWrite the cell reaction and n, write the Nernst equation, find E0cell, substitute the concentrations with the right powers, and give Ecell in volts. | Numericals | 2 | 5 papers | Specimen 2027 | Asked |
| 4 | Degree of dissociation (and Ka) of a weak electrolyteFind Lambda_m from kappa if needed, find Lambda0 from ionic values by Kohlrausch's law, compute alpha = Lambda_m / Lambda0, and if asked Ka = c alpha^2 / (1 - alpha). | Numericals | 3 | 5 papers | 2026 | Asked |
| 5 | Molar and equivalent conductivity from conductivity and concentrationConvert the mass or molarity to mol L-1 (and to normality for equivalent), apply Lambda_m = 1000 kappa / M and Lambda_eq = 1000 kappa / N, and give both with units. | Numericals | 2 | 5 papers | 2025 improvement | Asked |
| 6 | Give reasons: conductivity and molar conductivity on dilutionExplain why specific conductivity falls and molar conductivity rises on dilution, and why a weak electrolyte's molar conductivity rises sharply but a strong one's only gradually; judge assertion-reason items on this. | Give reason | 1 | 4 papers | 2026 | Asked |
| 7 | Spontaneity from signs of Ecell and delta GState the signs of Ecell and delta G for a spontaneous reaction and give the reason from delta G = -nFEcell; answer MCQ or fill-in forms of the same. | Give reason | 1 | 4 papers | 2025 improvement | Asked |
| 8 | Feasibility from E0: displacement, storage, H2 from acidDecide whether a given metal displaces H2 or another metal, or whether a solution can be stored in a metal vessel, and give the reason from E0 values; also judge assertion-reason items on the same idea. | Give reason | 1 | 3 papers | Specimen 2027 | Asked |
| 9 | Standard cell emf from two standard electrode potentialsIdentify anode and cathode from the E0 values, write E0cell = E0cathode - E0anode, and give the value with sign and unit. | Numericals | 1 | 3 papers | Specimen 2027 | Asked |
| 10 | State Kohlrausch's law and its applicationsState the law of independent migration of ions in words with the equation, and list its uses (Lambda0 of weak electrolytes, degree of dissociation, dissociation constant). | Statement | 1 | 3 papers | 2026 | Asked |
| 11 | Limiting molar conductivity of a salt from ionic valuesWrite Lambda0 of the salt as the sum of ionic conductivities each multiplied by its number in the formula, substitute, and give the value with units; compare two salts if asked. | Numericals | 1 | 3 papers | 2026 | Asked |
| 12 | Daniell cell: labelled diagram, electron, current and ion flowDraw and label the Zn-Cu cell with salt bridge, write the half-reaction at each electrode, mark the direction of electron flow, current and ion movement, and state the role of the salt bridge. | Diagram | 1 | 3 papers | 2025 | Asked |
| 13 | Electrochemical series: meaning and usesDefine the electrochemical series and state its uses: identifying anode and cathode, comparing oxidising and reducing power, predicting whether a metal liberates H2 from acid or displaces another metal. | Statement | 1 | 3 papers | 2025 improvement | Asked |
| 14 | Cell constant and conductivity from measured resistanceFind the cell constant from a standard KCl solution (cell constant = kappa x R), then use it to find the conductivity of another solution from its resistance. | Numericals | 2 | 3 papers | 2024 | Asked |
| 15 | Define resistivity, conductivity, cell constant, molar and equivalent conductivityWrite the definition with formula and SI or cgs unit for each term asked, including the fill-in form of the definitions. | Statement | 1 | 3 papers | 2020 | Asked |
| 16 | Lambda0 of one electrolyte from three othersWrite the required electrolyte as a sum and difference of the given strong electrolytes so that unwanted ions cancel, substitute with the right multipliers, and give Lambda0 with units. | Numericals | 3 | 2 papers | Specimen 2027 | Asked |
| 17 | Faraday's second law: cells in seriesFrom the mass deposited in one cell find the charge, then find the masses in the other cells by the ratio of equivalent masses (or via the same charge), writing each electrode reaction. | Numericals | 2 | 2 papers | Specimen 2027 | Asked |
| 18 | Nernst equation backwards: unknown concentration or E0cellGiven Ecell and all but one quantity, write the Nernst equation, rearrange for the unknown concentration or E0cell, and give the answer with the antilog step shown. | Numericals | 2 | 2 papers | 2025 | Asked |
| 19 | Order of reducing or oxidising power from E0 valuesArrange the given metals or ions in increasing or decreasing reducing (or oxidising) power and justify in one sentence from the reduction potentials. | Comparison | 2 | 1 paper | Specimen 2027 | Asked |
| 20 | Faraday's laws: statements, mathematical form, Z and EState both laws with their mathematical forms and define electrochemical equivalent (Z) and chemical equivalent, including fill-in forms. | Statement | 1 | 1 paper | Specimen 2027 | Asked |
| 21 | Case study on Kohlrausch's law: state, calculate, arrangeRead a short passage with ionic conductivities, then answer three 1-mark parts: state the law, calculate Lambda0 of a named salt, and arrange salts in order of Lambda0. | Give reason | 3 | 1 paper | 2026 | Asked |
| 22 | Galvanic cell with an external opposing voltageState what happens to the cell reaction and the current when the opposing voltage is less than, equal to, or greater than the cell emf. | Give reason | 1 | 1 paper | 2025 improvement | Asked |
| 23 | Primary vs secondary cells with examplesDefine primary and secondary cells, name an example of each, and give one advantage or disadvantage of a primary cell. | Statement | 1 | 1 paper | 2025 | Asked |
| 24 | H2-O2 fuel cell: reactions, advantages, disadvantagesDescribe the porous carbon electrodes with catalyst in KOH, write the anode, cathode and overall reactions, and give advantages and disadvantages. | Reaction | 1 | 1 paper | 2025 | Asked |
| 25 | Cell notation: write it, and read half-reactions from itConvert a cell reaction into standard cell notation (anode on the left, single line for phase boundary, double line for salt bridge) or read a given notation to write both half-reactions and the balanced overall cell reaction. | Reaction | 1 | 1 paper | 2024 | Asked |
| 26 | Leclanche dry cell: structure, reactions, usesDescribe or label the zinc container anode, graphite rod cathode and NH4Cl/ZnCl2/MnO2 paste, write the anode and cathode reactions, and give uses and a limitation. | Reaction | 1 | 1 paper | 2024 | Asked |
| 27 | Electrolysis: which ion is discharged first at an electrodeFor a solution with two cations (or anions), say which is discharged first at the electrode and why, using E0 values, and judge assertion-reason statements on it. | Give reason | 1 | 1 paper | 2023 | Asked |
| 28 | Galvanic vs electrolytic cell: energy change and differencesGive three or four points of difference (energy conversion, spontaneity, sign of anode and cathode, need for a salt bridge or external source) and fill one-line blanks on what each cell converts. | Comparison | 1 | 1 paper | 2018 | Asked |
| 29 | Corrosion: definition and electrochemical mechanism of rustingDefine corrosion and write the anodic and cathodic reactions on iron, the overall reaction and the formation of rust, explaining why it is an electrochemical cell. | Mechanism | 2 | 1 paper | 2018 | Asked |
| 30 | Standard hydrogen electrode: construction, use and limitationsDraw and label the SHE (platinised Pt, H2 at 1 bar, 1 M H+, 298 K), write its half-reaction and assigned E0 = 0, say how it is used as reference, and list its limitations. | Diagram | 1 | never | Never asked | |
| 31 | Measuring E0 of Zn2+/Zn and Cu2+/Cu against SHEDraw the cell of each half-cell coupled with the SHE, write its notation, say which is anode and which cathode from the voltmeter deflection, and explain why E0(Zn2+/Zn) is -0.76 V and E0(Cu2+/Cu) is +0.34 V. | Diagram | 2 | never | Never asked | |
| 32 | Factors affecting electrode potential: temperature, concentration, natureExplain in a line or two each how the nature of the metal, the ion concentration and the temperature change the electrode potential, using the Nernst form for the concentration effect. | Give reason | 1 | never | Never asked | |
| 33 | Nernst equation: potential of a single electrodeWrite the electrode reaction and n, write the Nernst equation for the half-cell, substitute E0 and the ion concentration, and give E in volts. | Numericals | 2 | never | Never asked | |
| 34 | Equilibrium constant from E0cell or delta G0Write the balanced reaction and n, use log K = nE0cell/0.0591 or delta G0 = -2.303RT log K, and give K (and delta G0 if asked). | Numericals | 2 | never | Never asked | |
| 35 | Metallic vs electrolytic conductanceGive the points of difference: charge carriers, chemical change, effect of temperature and of concentration. | Comparison | 1 | never | Never asked | |
| 36 | Graph: molar conductivity vs square root of concentrationSketch Lambda_m against sqrt(c) for a strong and a weak electrolyte on one set of axes, show the extrapolation to Lambda0 for the strong one, and say why Lambda0 of a weak electrolyte cannot be found this way. | Graph | 2 | never | Never asked | |
| 37 | Faraday constant, Avogadro number and electron chargeUse F = NA x e to find one quantity from the other two, or find the number of electrons in a given charge. | Numericals | 1 | never | Never asked | |
| 38 | Mercury cell: structure, reactions, usesDescribe the Zn-Hg amalgam anode and HgO/carbon paste cathode in KOH, write both electrode reactions and the overall reaction, and say why its voltage stays constant. | Reaction | 1 | never | Never asked | |
| 39 | Lead storage battery: discharge and recharge reactionsDescribe the Pb anode, PbO2 cathode and dilute H2SO4, write the anode, cathode and overall reactions on discharge, the reverse on charging, and give uses. | Reaction | 2 | never | Never asked | |
| 40 | Corrosion: factors and methods of preventionList the factors that speed up corrosion (moisture, dissolved salts, acids, impurities, contact with a less active metal) and explain methods of prevention such as painting, galvanising and sacrificial protection with the E0 reason. | Give reason | 1 | never | Never asked |
This list was made from the 2027 syllabus and checked with 9 board papers, including the 2027 specimen paper. It is not yet checked with the textbook.
The 10 topics Chemistry papers ask most
Counted on the board papers from 2018 to the 2027 specimen paper, which every unit has been checked against.
- 1.IUPAC names of coordination compounds from formulaC5 Coordination Compounds · asked 8 times since 2018
- 2.Faraday's first law: mass, charge, current or timeC2 Electrochemistry · asked 7 times since 2018
- 3.Give reasons: transition metal ions are coloured, some colourlessC4 d- and f-Block Elements · asked 7 times since 2018
- 4.Alcohols from Grignard reagent: 1, 2, 3 degreeC7 Alcohols, Phenols and Ethers · asked 7 times since 2018
- 5.Williamson's synthesis of ethersC7 Alcohols, Phenols and Ethers · asked 7 times since 2018
- 6.Identify A, B, C, D in a given reagent chainC8 Aldehydes, Ketones and Carboxylic Acids · asked 7 times since 2018
- 7.Identify compounds from formula and test results (case problem)C8 Aldehydes, Ketones and Carboxylic Acids · asked 7 times since 2018
- 8.Identify A, B, C: amide, Hoffmann and amine-test chainsC9 Organic Compounds containing Nitrogen · asked 7 times since 2018
- 9.Gibbs energy and maximum work from cell emfC2 Electrochemistry · asked 6 times since 2018
- 10.Coordination number and oxidation state of the central metalC5 Coordination Compounds · asked 6 times since 2018