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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C5 Coordination Compounds
All the topics in Chemistry: Coordination Compounds
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.
23 topics shown
| # | Topic | Type | Marks | Times asked | Last asked | Status |
|---|---|---|---|---|---|---|
| 1 | IUPAC names of coordination compounds from formulaWrite the IUPAC name: cation first, ligands in alphabetical order with di/tri or bis/tris prefixes, the metal (with -ate for an anionic complex), and the oxidation state in Roman numerals, then the anion. | Structure or name | 1 | 8 papers | Specimen 2027 | Asked |
| 2 | Identify the type of structural isomerism in a pairName the type of isomerism (ionisation, hydrate/solvate, linkage or coordination) shown by a given pair of complexes, with the one-line reason that shows which group has changed place. | Structure or name | 1 | 6 papers | Specimen 2027 | Asked |
| 3 | VBT of octahedral complexes: inner (d2sp3) vs outer (sp3d2)Find the oxidation state and d-electron count, draw the box diagram before and after ligand approach (pairing only for strong field ligands), and state hybridisation, inner or outer orbital, high or low spin, shape, unpaired electrons and magnetic behaviour. | Diagram | 2 | 6 papers | Specimen 2027 | Asked |
| 4 | Coordination number and oxidation state of the central metalCount donor atoms (not ligands) for the coordination number, and set up the charge balance x + sum of ligand charges = charge on the complex ion to find the oxidation state, for three complexes. | Numericals | 1 | 6 papers | 2026 | Asked |
| 5 | Deduce structural formula from AgCl moles or conductanceFrom the moles of AgCl precipitated or the number of ions from molar conductance, put the right number of Cl- outside the bracket, fill the sphere to coordination number 6, write the ionisation equation, and give the IUPAC name. | Structure or name | 2 | 5 papers | Specimen 2027 | Asked |
| 6 | VBT of four-coordinate complexes: tetrahedral sp3 vs square planar dsp2Draw the box diagram and state hybridisation, shape and magnetic behaviour of complexes such as [Ni(CO)4], [NiCl4]2-, [Ni(CN)4]2-, [Cu(NH3)4]2+ and [PtCl2(NH3)2]. | Diagram | 2 | 5 papers | Specimen 2027 | Asked |
| 7 | Chemical test to tell ionisation isomers apartName the ion outside the sphere in each isomer, give the reagent (AgNO3 for Cl-/Br-, BaCl2 for SO4 2-, FeSO4 + conc. H2SO4 for NO3-), and state the observation for each isomer. | Tell apart (test) | 2 | 4 papers | Specimen 2027 | Asked |
| 8 | Give reasons and evaluate claims: hybridisation and magnetismFor a statement or two students' answers, decide which is right and justify using the d-electron count, ligand field strength (pairing or not), hybridisation and number of unpaired electrons. | Give reason | 2 | 4 papers | Specimen 2027 | Asked |
| 9 | Five-mark question on one complex: name, isomers, test, structureAnswer a linked set of parts on one complex in about 10 minutes of exam time: IUPAC name, geometry, type of isomerism with structures, a chemical test for ionisation isomers, and the formula from AgCl or conductance data. | Give reason | 5 | 4 papers | Specimen 2027 | Asked |
| 10 | Geometrical (cis-trans, fac-mer) isomers: draw themDraw cis and trans forms of square planar MA2B2 and octahedral MA4B2 or [M(AA)2B2] complexes (and fac/mer for MA3B3), labelled, and say which complexes cannot show geometrical isomerism. | Structure or name | 2 | 3 papers | Specimen 2027 | Asked |
| 11 | d-electron configuration in octahedral field: high vs low spinWrite the t2g^x eg^y configuration of a d4 to d7 ion for delta-o < P and delta-o > P, count unpaired electrons, and say which configuration is low spin. | Diagram | 1 | 3 papers | Specimen 2027 | Asked |
| 12 | Strong and weak field ligands: spectrochemical series, delta-o vs PPlace given ligands on the spectrochemical series, relate ligand strength to the size of delta-o, and decide with reason whether a complex with a given configuration has strong or weak field ligands. | Give reason | 1 | 2 papers | Specimen 2027 | Asked |
| 13 | Uses: qualitative analysis, metal extraction, biology, medicineGive one named example with the complex involved for each use: qualitative analysis, extraction of metals, biological systems, medicine and estimation of hardness. | Statement | 1 | 2 papers | Specimen 2027 | Asked |
| 14 | Write the ionisation or linkage isomer of a given complexGiven one complex (or a formula like CoNO2Cl.5NH3 with a precipitation clue), write the structural formula of its isomer and name both by IUPAC. | Structure or name | 2 | 2 papers | 2026 | Asked |
| 15 | Stability constant K: explain stability and give reasonsWrite the formation equilibrium and expression for the stability constant, state that a larger K means a more stable complex, and use it to explain why a complex ion does not give the tests of its free metal ion or ligand (and the extra stability of chelates). | Give reason | 1 | 2 papers | 2026 | Asked |
| 16 | Werner's theory: postulates, primary and secondary valencyState the postulates of Werner's theory (primary ionisable valency = oxidation state, secondary non-ionisable valency = coordination number, secondary valencies are directional), and show them on the CoCl3.xNH3 series. | Statement | 1 | 1 paper | Specimen 2027 | Asked |
| 17 | Crystal field stabilisation energy from a configurationFrom the t2g and eg occupancies, compute CFSE = (-0.4 x + 0.6 y) delta-o (adding pairing energy P per extra pair only if asked), for three configurations, with sign. | Numericals | 1 | 1 paper | 2026 | Asked |
| 18 | Ligands by denticity: mono- to hexadentate, chelating, ambidentateClassify each given ligand as mono-, bi-, tri-, tetra-, penta- or hexadentate (or ambidentate), name its donor atoms, and say which are chelating ligands. | Statement | 1 | 1 paper | 2023 | Asked |
| 19 | Define coordination compound; differ from double saltDefine a coordination (complex) compound, name the central atom, ligands, coordination sphere and counter ion in a given formula, and give two differences from a double salt with one example of each. | Statement | 1 | never | Never asked | |
| 20 | Formula of a coordination compound from its IUPAC nameFrom a given IUPAC name, write the formula with the metal first, ligands in square brackets, counter ions outside, and check the charges balance. | Structure or name | 1 | never | Never asked | |
| 21 | Optical isomers of octahedral chelate complexesDraw the two non-superimposable mirror images of [Co(en)3]3+ or cis-[Co(en)2Cl2]+, and state why trans-[Co(en)2Cl2]+ is optically inactive; count total stereoisomers. | Structure or name | 2 | never | Never asked | |
| 22 | Crystal field splitting diagram: octahedral and tetrahedralDraw and label the splitting of the five d orbitals in octahedral (t2g below, eg above) and tetrahedral (e below, t2 above) fields, mark delta-o, delta-t and the energies -0.4 and +0.6 delta-o, and say why the order is reversed. | Diagram | 2 | never | Never asked | |
| 23 | Give reasons: colour and magnetism of complexes by CFTExplain colour as d-d transition absorbing visible light (seen colour is the complementary one), why d0 and d10 complexes and anhydrous CuSO4 are colourless, and how a ligand change alters colour and magnetic behaviour. | 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