If you want to know how to study Coordination Compounds for JEE — Main or Advanced — this guide is built entirely from real previous-year papers, not from a textbook chapter list. We pulled every Coordination Compounds question the NTA JEE Main and JEE Advanced examiners have asked in the most recent papers — 127 questions across JEE Main 2024, 2025 and 2026, plus 16 questions from JEE Advanced 2020–2026 — and sorted every single one into a sub-topic. What you're reading is the pattern that emerged, not a guess.
Coordination Compounds isn't just another Inorganic Chemistry chapter — it is currently the single highest-weightage chapter in the entire JEE Main 2026 syllabus across Physics, Chemistry and Maths combined, at 7.58%. That number comes directly from ExamSIDE's chapter-wise PYQ database, cross-checked against our own manual count of 354 questions asked since 2002. For a chapter this large, vague advice like "practice more" does nothing. You need to know exactly which sub-topic carries the most marks, which ones are pure memory, and which ones need real calculation practice — that's what this guide gives you.
Part of why this chapter carries so much weight is that it sits at the intersection of three different ways of thinking. It borrows electronic configuration and orbital-filling logic from Structure of Atom, it borrows periodic trends in oxidation states from d and f Block Elements, and then it layers a completely new set of rules on top — Werner's coordination sphere, VBT hybridization, and Crystal Field Theory — that don't exist anywhere else in the JEE Chemistry syllabus. Students who treat it as "more d-block memorisation" consistently underperform, because roughly half of the marks in this chapter come from applying a theory (CFT) rather than recalling a fact.
This also explains why NTA keeps returning to it every single session: it's one of the few Inorganic Chemistry chapters that supports genuine numerical, calculation-based questions (magnetic moment, CFSE) alongside pure conceptual ones (isomerism, nomenclature) — giving paper-setters flexibility to test both integer-answer and MCQ formats from the same syllabus section.
| Year | Questions (Numerical + MCQ) | Share of Chemistry PYQs that year |
|---|---|---|
| JEE Main 2024 | 48 (9 Numerical, 39 MCQ) | Highest of the three years |
| JEE Main 2025 | 43 (10 Numerical, 33 MCQ) | Slightly down from 2024 |
| JEE Main 2026 | 36 (10 Numerical, 26 MCQ) | 7.58% weightage, down 16.24% year-on-year |
ExamSIDE only publishes an exact weightage-and-trend figure for the current year (2026: 7.58%, down 16.24% from 2025), so we're not fabricating a percentage for 2024 and 2025 — but the raw question count tells its own story. The chapter has cooled slightly over three years (48 → 43 → 36 questions), yet it's still comfortably the biggest single chapter in JEE Main Chemistry. Even at its "lowest" in 2026, 36 questions in three years from one chapter is not a topic you can leave to the last week. Note also that Numerical (integer-type) questions have stayed remarkably stable at 9–10 per year — this is the one Chemistry chapter where NTA consistently sets aside a fixed numerical quota, almost always testing magnetic moment or AgCl-precipitation stoichiometry.
| Year | Numerical | MCQ (Single) | MCQ (Multi) | Total |
|---|---|---|---|---|
| 2020 | 0 | 0 | 2 | 2 |
| 2021 | 1 | 1 | 1 | 3 |
| 2022 | 0 | 1 | 0 | 1 |
| 2023 | 0 | 1 | 1 | 2 |
| 2024 | 3 | 1 | 0 | 4 |
| 2025 | 1 | 1 | 0 | 2 |
| 2026 | 2 | 0 | 0 | 2 |
Coordination Compounds carries a 5.88% weightage in JEE Advanced 2026 (down 5.92% from 2025 — a far gentler decline than JEE Main's). Since 1978, ExamSIDE records 59 total questions across 38 papers, and it hasn't skipped more than a year or two at a stretch since 2020. What's notable is the format mix: JEE Advanced leans much harder on "MCQ with more than one correct answer" and match-the-list formats than JEE Main does — of the 16 questions since 2020, only 5 are single-correct MCQs, versus 7 numericals and 4 multi-correct MCQs. If your Advanced prep is only single-correct-MCQ practice, you're training for the wrong format.
| Sub-topic | JEE Main (2024–26) | JEE Advanced (2020–26) | Combined |
|---|---|---|---|
| Magnetic Properties & Spin-only Moment | 44 | 4 | 48 |
| Crystal Field Theory, Colour & Electronic Configuration | 28 | 4 | 32 |
| Isomerism (Structural + Stereo) | 14 | 5 | 19 |
| Bonding, Hybridization & Geometry (VBT) | 14 | 3 | 17 |
| Nomenclature, Werner's Theory & Ligands | 16 | 0 | 16 |
| Applications & Organometallics | 7 | 0 | 7 |
4 of the 127 JEE Main questions (all from 2024 and 2026) referenced answer options/matching tables that the source's text extraction stripped of the actual chemical content (formulas rendered as blanks), so we could not confidently place them in a sub-topic without guessing — we've excluded them from the table above rather than force a category, and flag it here rather than smoothing the numbers to a round total.
One number should jump out immediately: Magnetic Properties & Spin-only Moment alone accounts for exactly one-third of every Coordination Compounds question asked (48 of 143 combined). No other sub-topic in this chapter comes close. Add Crystal Field Theory — which is really the "why" behind every magnetic moment answer — and these two closely-linked sub-topics together account for 56% of the entire chapter. If you master d-electron counting, high-spin/low-spin determination, and the spin-only formula cold, you have already secured the majority of this chapter's marks.
127 JEE Main questions in three years and a HIGH difficulty tag isn't a chapter to self-study from scratch. Our Chemistry HOD, AN Naik Sir, teaches this exact PYQ pattern 1-on-1.
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"Every year I get students in November who've 'finished' Coordination Compounds because they can recite Werner's postulates. Then I show them a 2026 numerical that chains ionization isomerism into an AgCl calculation into a magnetic moment, and they freeze — because they memorised three separate topics instead of learning how JEE connects them. This chapter rewards students who practice the combination questions, not the isolated definitions." — AN Naik Sir, HOD Chemistry, JEE Prep Master
The 2026 6th April Evening Shift question gives you a tetraaquadichloridochromium(III) chloride solution, its electrolyte type, and asks for moles of AgCl precipitated — pure Werner's-theory coordination-sphere reasoning. But the 2026 2nd April Morning Shift numerical goes further: it asks you to find the number of isoelectronic species first, use that count as the number of moles of AgCl formed, and then find electrons in a specific orbital of the resulting complex — three sub-topics stacked into one integer answer. This "chain" format barely existed before 2025 and is now common in Main numericals.
Across the 127 JEE Main questions we categorized, some variant of "find the spin-only magnetic moment" or "number of unpaired electrons" appears in nearly every single session paper — 18 of the 29 numericals (62%) in 2024–2026 test this directly. If you can only master one calculation in this chapter, this is it.
Real examples: the 2026 5th April Evening Shift question on t2g/eg stabilization energy values, the 2026 24th January Morning Shift question comparing paramagnetic species counts, and the 2025 2nd April Morning Shift question on high-spin/low-spin conditions are all framed as two-statement "choose the correct answer" questions rather than direct single-fact MCQs. This format tests whether you understand *why* CFT works, not just the final numbers.
The 2026 2nd April Morning Shift question matches four Cr(III) complexes — [Cr(CN)₆]³⁻, [CrF₆]³⁻, [Cr(H₂O)₆]³⁺, [Cr(en)₃]³⁺ — to their actual crystal field splitting energies in cm⁻¹, requiring you to know the spectrochemical series numerically, not just in order. Similarly, the 2025 8th April Evening Shift question matches four complexes to both their geometry and their magnetic moment in one table. These match-list questions are worth full marks only if every row is correct — partial knowledge of the spectrochemical series isn't enough.
Contrast the JEE Main pattern above with JEE Advanced: the 2024 Paper 1 question about ionization isomer sets, the 2023 Paper 2 question on isomerism types, and the 2020 Paper 2 Gouy-balance magnetic-deflection experiment question test conceptual identification, not plug-into-formula calculation. If your Advanced prep is just "more numerical practice," you're preparing for the wrong exam's style.
The formula is non-negotiable: μ = √n(n+2) BM, where n is the number of unpaired electrons. Every mistake students make here traces back to one thing — miscounting n. For d1–d3 and d8–d10 configurations, there's only one possible arrangement regardless of ligand field strength, so magnetic moment is fixed. The danger zone is d4 to d7: here, the ligand's position in the spectrochemical series decides whether you get a high-spin or low-spin arrangement, and that changes n. Build a habit: before calculating anything, write out the free-ion d-electron count, identify the ligand as weak-field or strong-field, then fill t2g and eg accordingly for octahedral geometry (or the tetrahedral e/t2 set if geometry is tetrahedral). Only then apply the formula. Practice on real PYQs like the 2025 7th April Evening Shift question (four complex ions, four magnetic moments to match) until this sequence is automatic.
Worked example: Find the spin-only magnetic moment of [CoF₆]³⁻. Co³⁺ is d6. F⁻ is a weak-field ligand, so this is a high-spin octahedral complex: fill all five d-orbitals singly before pairing (Hund's rule dominates over pairing energy) — t2g⁴eg² arrangement means 4 unpaired electrons. μ = √4(4+2) = √24 ≈ 4.90 BM. Now compare this to [Co(NH₃)₆]³⁺, also Co³⁺ (d6), but NH₃ is a strong-field ligand — this is low-spin: t2g⁶eg⁰, all electrons paired, 0 unpaired electrons, μ = 0 BM (diamagnetic). Same metal, same oxidation state, same d-electron count — completely different answer, purely because of ligand field strength. This exact contrast is what the 2026 24th January Morning Shift Statement I/II question is built around.
CFSE for an octahedral field is CFSE = [-0.4 × n(t2g) + 0.6 × n(eg)] Δ₀ (minus any pairing energy penalty for forced pairing under a strong field). For tetrahedral fields, CFSE = [-0.6 × n(e) + 0.4 × n(t2)] Δt, and remember Δt is always smaller — roughly (4/9)Δ₀ — which is exactly why low-spin tetrahedral complexes are essentially never seen in JEE. Colour in coordination compounds comes from d-d transitions: a larger Δ₀ means the complex absorbs higher-energy (shorter-wavelength) light and appears in the complementary colour. Learn the spectrochemical series in order — I⁻ < Br⁻ < S²⁻ < SCN⁻ < Cl⁻ < F⁻ < OH⁻ < C₂O₄²⁻ < H₂O < NCS⁻ < py < NH₃ < en < NO₂⁻ < CN⁻ < CO — not just as a list to recite, but as a scale you can use to instantly judge whether a given ligand will produce a high-spin or low-spin complex, and which of two complexes absorbs at a longer wavelength.
Worked example: Compare CFSE for [Ti(H₂O)₆]³⁺ and a hypothetical strong-field version of the same ion. Ti³⁺ is d1 — the single electron always goes into t2g regardless of field strength. CFSE = -0.4 × 1 × Δ₀ = -0.4Δ₀. Since there's only one electron, pairing energy never enters the picture, which is exactly why d1 complexes never have a "high-spin vs low-spin" debate — that question only becomes meaningful from d4 onward, where you must compare the pairing energy (P) against Δ₀: if Δ₀ > P, electrons pair up in t2g first (low spin); if Δ₀ < P, they spread into eg first (high spin). This P-versus-Δ₀ comparison is the single most tested reasoning step in this entire sub-topic.
Split this into two buckets. Structural isomerism covers ionization isomerism (different ions inside vs outside the coordination sphere, e.g. [Co(NH₃)₅Br]SO₄ vs [Co(NH₃)₅SO₄]Br), linkage isomerism (an ambidentate ligand like NO₂⁻/ONO⁻ or SCN⁻/NCS⁻ binding through a different atom), coordination isomerism (ligand redistribution between cationic and anionic complexes in a salt), and hydrate isomerism. Stereoisomerism covers geometrical isomerism (cis/trans for MA₄B₂ and MA₃B₃ types, including facial and meridional arrangements) and optical isomerism, which appears almost exclusively in octahedral complexes with chelating bidentate ligands like [M(en)₃]ⁿ⁺ or [M(en)₂X₂]ⁿ⁺ — these lack a plane of symmetry and exist as non-superimposable mirror images. The 2026 Advanced Paper 2 numerical on cis- and mer- octahedral triangular faces is a direct test of visualising these 3D structures, not memorising a rule.
Worked example: Take [Co(en)₂Cl₂]⁺. This is an MA₂B₂-type complex with two bidentate en ligands and two monodentate Cl⁻ ligands, giving it two geometrical isomers: cis (Cl atoms adjacent, 90° apart) and trans (Cl atoms opposite, 180° apart). Now check each for optical activity: the trans isomer has a plane of symmetry passing through both Cl atoms and is optically inactive (achiral). The cis isomer has no such plane — it is chiral, and exists as a pair of non-superimposable mirror-image enantiomers. So this single molecular formula actually represents three distinct isomers in total (1 trans + 2 cis-enantiomers), a counting trap that the 2023 Advanced Paper 1 match-list question and several Main MCQs exploit directly.
Valence Bond Theory ties hybridization directly to geometry and magnetic behaviour: sp³ gives tetrahedral (e.g. [NiCl₄]²⁻, paramagnetic), dsp² gives square planar (e.g. [Ni(CN)₄]²⁻, diamagnetic), and octahedral complexes split into two cases that trip up most students — inner-orbital complexes use d²sp³ hybridization (using inner (n-1)d orbitals, giving low-spin, e.g. [Co(NH₃)₆]³⁺) while outer-orbital complexes use sp³d² (using outer nd orbitals, giving high-spin, e.g. [CoF₆]³⁻). The 2026 23rd January Evening Shift question tests exactly this inner-vs-outer distinction across five complexes simultaneously — memorise the rule, don't derive it under exam pressure.
Werner's postulates define primary valency (the oxidation state — ionizable, satisfied by anions) and secondary valency (the coordination number — non-ionizable, satisfied by ligands occupying fixed geometric positions). IUPAC naming follows a strict order: cationic ligands are never separately named, ligands are named alphabetically regardless of charge or number (with multiplying prefixes di-/tri-/tetra- for simple ligands and bis-/tris-/tetrakis- for complex or already-prefixed ligand names like ethylenediamine), the metal is named last with its oxidation state in Roman numerals in brackets, and anionic complexes always end in "-ate." Know your ligand denticity: monodentate (NH₃, Cl⁻), bidentate (en, oxalate, DMG), hexadentate (EDTA⁴⁻, which the 2020 September numerical tests directly by asking for its total coordination sites).
Worked example: Name [Pt(NH₃)₂Cl₂]. Ligands first, alphabetically: "ammine" (NH₃) comes before "chlorido" (Cl⁻), so it's diamminedichlorido — using di- because there's no ambiguity (simple ligand names take di-/tri-/tetra-, not bis-/tris-). Metal next, with oxidation state: Pt here is +2 (two neutral NH₃ contribute 0, two Cl⁻ contribute -2 charge, complex is neutral overall), so platinum(II). Full name: diamminedichloridoplatinum(II) — no space before the Roman numeral, no separate naming for the neutral ligands' charge. This is the exact complex behind cisplatin, and getting the naming sequence wrong (metal before ligands, or alphabetising by prefix instead of ligand name) is the most common error the 2024 6th April Evening Shift IUPAC-naming MCQ was built to catch.
This is the smallest bucket but still shows up reliably. Know metal carbonyls and synergic bonding: the metal-carbon bond has both a σ-component (CO's lone pair donating into an empty metal orbital) and a π-component (the metal's filled d-orbital back-donating into CO's empty π* orbital) — this synergic interaction is what makes compounds like Ni(CO)₄ and Mn₂(CO)₁₀ stable. Also know the real-world/biological applications JEE likes to test: EDTA in treating heavy-metal poisoning and water hardness, cisplatin as an anticancer drug, Wilkinson's catalyst ([RhCl(PPh₃)₃]) in hydrogenation, chlorophyll (Mg) and haemoglobin (Fe) as biological coordination compounds, and the Ni-DMG red precipitate used in qualitative analysis for nickel detection — the same reaction the 2024 29th January Evening Shift MCQ tests directly ("a reagent which gives brilliant red precipitate with Nickel ions in basic medium"). This sub-topic rewards a short, dedicated memory pass rather than deep derivation: build a single reference table of ligand → application → real-world use case (EDTA → lead/mercury poisoning treatment and water-hardness titration; cisplatin → testicular and ovarian cancer chemotherapy; Wilkinson's catalyst → alkene hydrogenation in industrial synthesis; chlorophyll/haemoglobin → photosynthesis/oxygen transport) and you'll have covered nearly every angle JEE has asked from this bucket across the last three years.
Reading through six sub-topics is one thing — knowing which one to prioritise under exam pressure is another. AN Naik Sir walks students through this exact priority order (Magnetic Properties → CFT → Isomerism → VBT → Nomenclature → Applications) in a single 1-on-1 session.
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| Concept | Formula / Rule |
|---|---|
| Spin-only magnetic moment | μ = √n(n+2) BM, where n = unpaired electrons |
| Octahedral CFSE | [-0.4 × n(t2g) + 0.6 × n(eg)] Δ₀ |
| Tetrahedral CFSE | [-0.6 × n(e) + 0.4 × n(t2)] Δt, where Δt ≈ (4/9)Δ₀ |
| Werner's primary valency | = oxidation state (ionizable) |
| Werner's secondary valency | = coordination number (non-ionizable) |
| Inner-orbital complex (VBT) | d²sp³ hybridization, low spin |
| Outer-orbital complex (VBT) | sp³d² hybridization, high spin |
| Spectrochemical series (weak → strong) | I⁻ < Br⁻ < SCN⁻ < Cl⁻ < F⁻ < OH⁻ < H₂O < NH₃ < en < CN⁻ < CO |
JEE Advanced has consistently avoided repeating JEE Main's numerical-calculation style for this chapter. Instead, recent papers combine multiple properties of the same complex into one question: the 2022 Paper 1 match-the-list question requires you to simultaneously identify t2g-orbital electron count, spin-only magnetic moment, whether a complex is low-spin, and the metal's oxidation state — four sub-topics collapsed into a single list-matching exercise. The 2017 Paper 1 multi-correct question goes even further, walking through an entire synthesis (pink Co²⁺ solution → octahedral complex X in air → blue complex Y with excess HCl) and asking you to verify magnetic moments and electrolyte behaviour at each step — you need the full reaction logic, not an isolated fact. If you're targeting Advanced, practice identifying which sub-topics a single complex touches simultaneously, because that's exactly how the exam tests it.
There's also a format shift worth noting across the full 1978–2026 archive: the two Subjective questions in this chapter's history are both from 2005, before JEE Advanced replaced the old IIT-JEE subjective-answer format entirely. Since then, the chapter has moved almost exclusively into MCQ (single and multi-correct) and, from 2013 onward, integer-type numericals — mirroring JEE Main's own shift but arriving at it through match-the-list and multi-correct formats rather than Main's chain-numericals. If you're preparing from an older solved-paper book that still has long subjective derivations for this chapter, treat it as background understanding only — it's not the format you'll actually face.
This is our first Chemistry chapter guide after six Physics chapters (Electrostatics, Magnetism, Electromagnetic Induction, Alternating Current, Electromagnetic Waves, and Ray Optics), and the contrast is worth naming. Those Physics chapters reward derivation-and-formula-application — you apply one core relationship (Faraday's law, Biot-Savart, the mirror/lens equation) to a new geometric setup each time. Coordination Compounds rewards concept-recall combined with light stoichiometry: 33% of every question tests one formula (spin-only magnetic moment), but getting to the right inputs for that formula requires recalling Werner's theory, the spectrochemical series, and hybridization rules correctly first. In terms of raw weightage, Coordination Compounds (7.58% in JEE Main 2026) is also higher than every Physics chapter we've covered so far — Electrostatics sits at 5.47%, Electromagnetic Induction and Alternating Current are both under 5%. If you're deciding where to invest revision hours across subjects, this chapter currently outranks all of them.
There's a second contrast worth flagging for anyone reading both guides back to back: our Electrostatics guide found that chapter's PYQs cluster heavily around Gauss's Law and dipole-field numericals — a narrow set of derivations applied repeatedly. Coordination Compounds spreads much more evenly across six distinct sub-topics, with no single sub-topic exceeding 34% of the total (Magnetic Properties, at 48 of 143). That breadth is exactly why a chapter-wise study plan matters more here than almost anywhere else in JEE Chemistry — you cannot "spot" this chapter by mastering one derivation and hoping it repeats.
Week 1 — Foundations: Days 1–2: Werner's postulates, primary vs secondary valency, coordination number and denticity. Days 3–4: IUPAC nomenclature rules, practice naming 15–20 real complexes from PYQs. Days 5–7: Structural isomerism (ionization, linkage, coordination, hydrate) with one worked PYQ example per type.
Week 2 — Stereoisomerism: Days 1–3: Geometrical isomerism for MA₄B₂ and MA₃B₃ types, facial vs meridional. Days 4–6: Optical isomerism in [M(en)₃]ⁿ⁺ and [M(en)₂X₂]ⁿ⁺ complexes — practice drawing mirror images. Day 7: Mixed isomerism PYQ set (2024–2026 Main + 2020–2026 Advanced), timed.
Week 3 — Bonding theories (the heaviest week): Days 1–2: VBT hybridization rules, inner vs outer orbital complexes. Days 3–5: Crystal Field Theory — splitting diagrams, CFSE calculation for both octahedral and tetrahedral fields, high-spin/low-spin determination. Days 6–7: Spectrochemical series and colour/wavelength questions, drilled until instant recall.
Week 4 — Magnetism, applications, and full drilling: Days 1–2: Spin-only magnetic moment mastery — 20+ practice problems covering d1 through d9. Day 3: Metal carbonyls, synergic bonding, EDTA and biological applications. Days 4–5: Full timed PYQ sets from JEE Main 2024, 2025, 2026. Days 6–7: JEE Advanced 2020–2026 questions, error log review, and re-attempt every question you got wrong in Weeks 1–3.
A dedicated 1-on-1 track with our HOD covers the same 4 weeks of content in focused sessions, with PYQ-by-PYQ feedback instead of self-checking your own answers.
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Every mistake above is one AN Naik Sir sees repeated every session — and corrects in the first hour of 1-on-1 coaching, before it costs you marks on an actual paper.
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Yes — it's currently the highest-weightage chapter in the entire JEE Main 2026 syllabus at 7.58%, ahead of every Physics and Maths chapter. With 127 questions across just the last three years, it offers a very high return on focused study time.
Based on our 2024–2026 analysis: 48 questions in 2024, 43 in 2025, and 36 in 2026 (across all sessions combined) — roughly 2–3 questions worth of marks in any single session paper.
Yes. It carries a 5.88% weightage in JEE Advanced 2026 and has appeared in some form virtually every year since 2020, though the question style leans toward conceptual identification and match-the-list formats rather than JEE Main's numerical-calculation style.
Nomenclature, Werner's theory, and ligand classification — it's pure memory with no calculation, and it's the foundation every other sub-topic (isomerism, CFT, magnetism) builds on.
The spin-only magnetic moment formula and the process of correctly determining high-spin vs low-spin electron configuration before applying it. This one skill, combined with CFT, accounts for 56% of all Coordination Compounds marks in our combined PYQ data.
Not entirely — it appears regularly in Main's isomerism questions, and skipping it removes your ability to answer any question involving [M(en)₃]ⁿ⁺-type complexes, which are common. For Advanced, it's non-negotiable.
d and f Block Elements covers the properties, trends, and chemistry of the transition metals themselves (electronic configuration trends, oxidation states, alloys). Coordination Compounds covers how those metals bond with ligands to form complex ions — the two are related but tested separately, and ExamSIDE tracks them as distinct chapters.
Given its 7.58% JEE Main weightage — the highest of any chapter in the syllabus — it deserves at least as much revision time as any two average-weightage chapters combined, roughly 4 full weeks if starting from scratch, or 5–6 focused days for pure revision.
Yes, meaningfully. JEE Main leans on integer-type numericals that chain 2–3 concepts (electrolyte type → AgCl stoichiometry → magnetic moment), while JEE Advanced favours match-the-list and multi-correct MCQs that test conceptual identification across several properties of the same complex at once. Prepare for both formats separately rather than assuming one style covers the other.
Magnetic Properties & Spin-only Magnetic Moment — not because it's hardest, but because it's the most frequently tested (48 of 143 combined PYQs) and the fastest to refresh: a 20-minute review of d-electron counting and the μ = √n(n+2) formula the night before covers the single largest chunk of this chapter's marks.
Coordination Compounds is not a chapter you can pattern-match your way through with generic advice. The data is unambiguous: master spin-only magnetic moment and Crystal Field Theory first, because together they carry the majority of the marks; then build isomerism, VBT hybridization, nomenclature, and applications on top in that order of PYQ frequency. This guide was built by pulling every JEE Main question from 2024–2026 and every JEE Advanced question from 2020–2026 directly from ExamSIDE's chapter-wise archives, manually reading and classifying all 143 questions into six sub-topics, and cross-checking our counts against ExamSIDE's own published aggregate totals (354 JEE Main questions since 2002, 59 JEE Advanced questions since 1978) — they matched. Where four questions couldn't be confidently classified due to missing formula text in the source, we said so rather than forcing a number.
