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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C1 Solutions
All the topics in Chemistry: Solutions
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.
33 topics shown
| # | Topic | Type | Marks | Times asked | Last asked | Status |
|---|---|---|---|---|---|---|
| 1 | Degree of association of a dimerising soluteFrom delta-Tf or delta-Tb find the observed molar mass, then i = normal M/observed M, then alpha = (1 - i)/(1 - 1/n) with n = 2, as a fraction or percentage. | Numericals | 2 | 5 papers | Specimen 2027 | Asked |
| 2 | Order solutions by colligative property using number of particlesFor each solution find i and the effective particle concentration (i x C, or moles of particles), then arrange freezing points, boiling points, osmotic pressures or i values in the asked order, with a reason. | Comparison | 1 | 5 papers | Specimen 2027 | Asked |
| 3 | Abnormal molecular mass: predict and justify association or dissociationSay whether a solute associates or dissociates (from given data or its nature), and justify how this changes the number of particles, the colligative property and the observed molar mass compared with the normal value. | Give reason | 1 | 4 papers | Specimen 2027 | Asked |
| 4 | Colligative property of an electrolyte using modified formula with iFind i for complete dissociation from the formula, then use pi = iCRT or delta-T = i K m to get the osmotic pressure, boiling or freezing point, or the observed molar mass. | Numericals | 2 | 4 papers | Specimen 2027 | Asked |
| 5 | Degree of dissociation of an electrolyte from colligative dataFrom the measured property find the observed molar mass (or i = observed delta-T / calculated delta-T), then i = normal M/observed M, then alpha = (i - 1)/(n - 1) as a fraction or percentage. | Numericals | 2 | 4 papers | Specimen 2027 | Asked |
| 6 | Molar mass of a solute (protein, polymer) from osmotic pressureRearrange pi = wRT/(MV) for M, convert mL to L, degC to K and mm Hg to atm if needed, and give M in g mol-1. | Numericals | 2 | 3 papers | Specimen 2027 | Asked |
| 7 | Freezing point depression: molar mass, mass of solute or molalityFind delta-Tf, write delta-Tf = Kf m, rearrange for the unknown (molality, molar mass, or mass of solute to dissolve) and substitute with units. | Numericals | 2 | 3 papers | 2026 | Asked |
| 8 | Assertion-reason and true-statement items on colligative propertiesJudge each statement or assertion and reason about vapour pressure, freezing point, osmotic pressure and number of particles, and choose the option with a one-line reason. | Give reason | 1 | 3 papers | 2026 | Asked |
| 9 | Osmotic pressure of a solution from mass and volumeFind moles of solute, convert volume to litres and temperature to K, use pi = (w/M)RT/V with R = 0.0821 L atm K-1 mol-1, and give pi in atm. | Numericals | 2 | 3 papers | 2026 | Asked |
| 10 | Relative lowering of VP: solution VP or molar massWrite (p0 - p)/p0 = n2/(n1 + n2) (or n2/n1 for dilute), substitute moles from the masses, and give the vapour pressure of the solution or the molar mass of the solute with units. | Numericals | 2 | 3 papers | 2025 improvement | Asked |
| 11 | Boiling point elevation: boiling point of solution or molar massFind delta-Tb from the given temperatures, write delta-Tb = Kb m, substitute masses in g and kg correctly, and give the boiling point of the solution or the molar mass of a non-electrolyte with units. | Numericals | 2 | 3 papers | 2025 improvement | Asked |
| 12 | Linking colligative properties: one measured, find anotherFrom one measured property (e.g. freezing point) find the molality, then use it to find another (boiling point, lowering of vapour pressure or molar mass and freezing point) in the same solution. | Numericals | 2 | 3 papers | 2025 improvement | Asked |
| 13 | Case study: isotonic, hypotonic, hypertonic solutions in living cellsDefine isotonic, hypotonic and hypertonic, then predict and explain what happens to a cell, egg or tissue placed in a given solution, or why a medical or diet advice is given, in terms of the direction of water flow. | Give reason | 1 | 3 papers | 2025 improvement | Asked |
| 14 | Henry's law: statement and everyday applications with reasonsState Henry's law in words and as an equation, then explain each case (soda bottles, aquatic life in cold water, divers and the bends, low oxygen at altitude) by the effect of pressure or temperature on gas solubility. | Give reason | 1 | 2 papers | 2026 | Asked |
| 15 | Ideal and non-ideal solutions: conditions, deviations and examplesDefine ideal and non-ideal solutions, give the conditions (delta-H mix = 0, delta-V mix = 0, A-B forces equal to A-A and B-B), explain positive and negative deviation by forces, and give two examples of each type. | Comparison | 1 | 2 papers | 2025 improvement | Asked |
| 16 | Isotonic solutions: molar mass or mass of solute neededSet C1 = C2 (equal osmotic pressure at the same temperature), substitute the masses and volumes or the given osmotic pressure, and solve for the unknown molar mass or mass per litre. | Numericals | 2 | 2 papers | 2024 | Asked |
| 17 | Mole fraction, molality and molarity from given massesConvert each mass to moles with the molar mass shown, then write the formula and substitute to get mole fraction of each component (checking they add to 1), molality or molarity with units. | Numericals | 2 | 1 paper | Specimen 2027 | Asked |
| 18 | Azeotropes: type from deviation, with justificationDefine an azeotrope, say whether a given pair forms a minimum- or maximum-boiling azeotrope, and justify from the change in intermolecular forces on mixing and the sign of the deviation. | Give reason | 1 | 1 paper | Specimen 2027 | Asked |
| 19 | Raoult's law for volatile and non-volatile solutesState Raoult's law for a solution of two volatile liquids and for a non-volatile solute, with the equation for each and the meaning of every symbol. | Statement | 1 | 1 paper | 2025 improvement | Asked |
| 20 | Vapour pressure, volatility and boiling point: give reasonsCompare two liquids (or a liquid and a solution) and explain in one or two lines how boiling point, intermolecular forces and vapour pressure at a given temperature are linked. | Give reason | 1 | 1 paper | 2025 improvement | Asked |
| 21 | Osmosis and osmotic pressure: definitions, SPMs, diffusion vs osmosisDefine osmosis and osmotic pressure, give natural and chemical semipermeable membranes, tabulate at least three differences between diffusion and osmosis, and show from pi = CRT that osmotic pressure is a colligative property. | Statement | 1 | 1 paper | 2025 | Asked |
| 22 | Reverse osmosis and desalination of sea waterExplain that a pressure greater than the osmotic pressure applied on the solution side drives solvent out through the membrane, and describe its use to get drinking water from sea water, naming a suitable membrane. | Statement | 1 | 1 paper | 2025 | Asked |
| 23 | van't Hoff factor from degree of dissociation or associationWrite the particle count before and after (or the formula for i in terms of alpha and n), substitute alpha and n for the given solute, and give i. | Numericals | 1 | 1 paper | 2025 | Asked |
| 24 | Types of solutions with examples; define concentration termsName the solute and solvent phase for solid-in-liquid, liquid-in-liquid, gas-in-liquid and solid solutions with one example each, and define normality, molality, molarity, mole fraction and ppm with units. | Statement | 1 | never | Never asked | |
| 25 | Normality, ppm and molarity-to-molality conversion using densityFind gram equivalents from the n-factor for normality, ppm from mass ratio, and convert molarity to molality by finding mass of solution from density and subtracting solute mass. | Numericals | 2 | never | Never asked | |
| 26 | Henry's law: solubility or mole fraction of a gasWrite p = KH x, substitute partial pressure and KH in matching units, find the mole fraction of the gas and, if asked, convert to moles or mass in the given amount of water. | Numericals | 2 | never | Never asked | |
| 27 | Vapour pressure and vapour composition of two volatile liquidsFind mole fractions in the liquid, use Raoult's law for each partial pressure, add for total pressure, and use Dalton's law to give the mole fraction of each component in the vapour. | Numericals | 2 | never | Never asked | |
| 28 | Vapour pressure-composition graphs: ideal, positive and negative deviationDraw labelled vapour pressure versus mole fraction plots showing pA, pB and total pressure for an ideal solution, and the total curve above or below the ideal line for positive and negative deviation. | Graph | 2 | never | Never asked | |
| 29 | Boiling point-composition diagram and fractional distillation of azeotropesSketch the boiling point versus composition diagram for a minimum- or maximum-boiling azeotrope, mark the azeotropic point, and explain what fractional distillation gives as distillate and residue and why the azeotrope cannot be separated further. | Graph | 2 | never | Never asked | |
| 30 | Colligative properties: definition, the four properties and examplesDefine a colligative property, name the four, and explain why each depends only on the number of solute particles, with an everyday example such as salting roads or antifreeze. | Statement | 1 | never | Never asked | |
| 31 | Derive delta-Tb = Kb m; define ebullioscopic constantDraw the vapour pressure versus temperature graph for solvent and solution, show delta-Tb is proportional to lowering of VP and hence to molality, reach delta-Tb = Kb m and M2 = 1000 Kb w2/(delta-Tb W1), and define Kb with its unit. | Derivation | 3 | never | Never asked | |
| 32 | Derive delta-Tf = Kf m; define cryoscopic constantDraw the vapour pressure versus temperature graph showing solid solvent, liquid solvent and solution curves, explain why the freezing point falls, reach delta-Tf = Kf m and M2 = 1000 Kf w2/(delta-Tf W1), and define Kf with its unit. | Derivation | 3 | never | Never asked | |
| 33 | van't Hoff laws of osmotic pressure (Boyle, Charles, Avogadro)State van't Hoff-Boyle's, van't Hoff-Charles' and van't Hoff-Avogadro's laws for dilute solutions and combine them into pi V = nRT. | Statement | 2 | 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