HSC 2026 published Aug 2026

Chemistry question styles to look out for

The question styles to have ready — each linked to its evidence and to a question in the practice paper.

Built by a six-model AI panel and backtested against the hidden 2025 papers — how we did it.

About the 2026 exam & how this page was built

Built from a six-model AI analysis of every HSC Chemistry paper, marking guideline and marking-centre feedback report since 2019 — backtested against the 2025 paper before we published it. These are styles to prepare for, not guarantees: our backtest showed the examiners keep the skill and twist the format, so practise the skill chain, not a memorised question.

Section II · 6–9 marks 6 of 6 models expect this

Structure elucidation from combined spectra — the capstone

The 6–9 mark late-paper capstone reverts from 2025's "predict the spectra" inversion to classic structure determination: an unknown C4–C6 oxygenate (ester, ketone or amide) presented with...

Try it → Q37 Why we expect this

Section II · 4–8 marks 6 of 6 models expect this

Organic reaction pathway flow chart (alkene → alcohol → carbonyl → ester)

A flow chart or reactivity list from an alkene or haloalkane through hydration/substitution, oxidation, and esterification; students draw structures A–D and state reagents and conditions.

Try it → Q35 Why we expect this

Section II · 3–6 marks 6 of 6 models expect this

Collision theory where Le Chatelier isn't enough

A disturbance (species added/removed, or temperature change with an energy-profile diagram supplied) to a gaseous or coloured equilibrium; students must explain the response through...

Try it → Q24 Why we expect this

On this page

1. Structure elucidation from combined spectra — the capstone
2. The big titration — back-titration with an outlier
3. ICE-table Keq — with the added amount as the unknown
4. Collision theory where Le Chatelier isn't enough
5. The instrument calibration curve
Where to spend study time
Practice paper
Check our working

The big five (have these cold)

1. Structure elucidation from combined spectra — the capstone

What it looks like: a 6–9 mark question near the end of the paper: an unknown C4–C6 compound with a mass spectrum, IR trace, ¹³C spectrum and a ¹H NMR table. You draw, name and justify the structure from at least three spectra.
Why we expect it: it has anchored every paper since 2019. In 2025 the examiners inverted it (gave the structure, asked for the spectra) — the panel strongly expects reversion to the classic form, but prepare both directions.
The traps markers flag (2021, 2022, 2023, 2024): confusing the base peak with the parent ion; reading integration as splitting (and vice versa); counting atoms instead of chemical environments.
Practise: one unknown per week from combined spectra; write the justification linking each structural feature to a specific spectral signal.

Try it → Q37 6 of 6 models expect this — see the evidence

2. The big titration — back-titration with an outlier

What it looks like: 6–8 marks on a consumer product (antacid, fertiliser, vinegar, aspirin): a standardisation or excess-reagent step, four titres with one obvious outlier, a dilution factor, ending in a verdict on the label claim.
Why we expect it: the 2021/2023/2025 pattern — and in our 2025 backtest, five of six models called it and the real Q33 was exactly this (7 marks).
The traps (flagged 2021, 2022, 2023, 2025): not excluding the outlier titre; breaking the mole-ratio chain mid-calculation; rounding early.
Practise: full back-titrations done end-to-end with clean setting-out — markers reward the visible chain of reasoning.

Try it → Q31 5 of 6 models expect this — see the evidence

3. ICE-table Keq — with the added amount as the unknown

What it looks like: a gaseous equilibrium with Keq given; something is added to the vessel and you must find how much, working the ICE table backwards from a stated new equilibrium concentration.
Why we expect it: this calculation ran every year 2019–2024 and then vanished from 2025 — it is the single most "due" calculation on the paper.
The traps (2021, 2024): using moles where concentrations are needed; mishandling exponents in the Keq expression.

Try it → Q25 5 of 6 models expect this — see the evidence

4. Collision theory where Le Chatelier isn't enough

What it looks like: a disturbance to an equilibrium (often with an energy profile supplied); you must explain the response through collision frequency and the unequal changes to forward and reverse rates.
Why we expect it: the marking centre has flagged bare-Le-Chatelier answers in four of the last six feedback reports; 2025's Q35 escalated the demand.
The trap: "the equilibrium shifts right to oppose the change" scores almost nothing on these. Name the rates. Reference the activation energies.

Try it → Q24 6 of 6 models expect this — see the evidence

5. The instrument calibration curve

What it looks like: AAS or colorimetry calibration line, a diluted sample, 4–7 marks: interpolate, reverse the dilution, convert mol L⁻¹ ↔ mg L⁻¹, judge against a water-quality limit.
The traps: applying the dilution factor backwards; unit conversion slips.

Try it → Q27 5 of 6 models expect this — see the evidence

Also on the radar

Salt hydrolysis pH (Ka↔Kb via Kw, ICE with a justified approximation) — the exact style of 2025's Q31(b); still live.
Conductometric titration graphs — explain the V-shape naming the actual ions and their mobilities; "ions change" scores nothing.
Flawed ion-testing sequences — the harder variant: say why a given sequence returns a false result and redesign it, with net ionic equations.
Calorimetry — absent in 2025 for the first time in six years; if it returns, expect a twist in the q = mcΔT mass (solution density, or CO₂ loss).
Organic reaction pathways — flow charts where a tertiary alcohol resists oxidation; know your reagents and conditions cold.
IUPAC naming multiple choice — distractors are built from numbering from the wrong end, the wrong parent chain, and non-alphabetical substituents.

Where to spend less time

The panel's one "rested" call: chemical synthesis and design dominated 2025 and is the least likely module to carry heavy marks in 2026 (lowest consensus probability of all eleven areas). Know it — everything is examinable — but don't build your revision around it.

The honest fine print

When we backtested this method on the 2025 paper, our high-confidence topic calls went 37/37, and about half of our specific question predictions recognisably appeared — but the examiners inverted formats, migrated questions to multiple choice, and broke two long streaks. Prepare the skill chains above, not memorised questions, and you're covered either way.

Want to check our working? every call above, with each model's own prediction

Structure elucidation capstone from combined spectra 6 of 6 models expect this

chem-q1-spectroscopy-capstone Section II 6–9 marks discriminator consensus 0.72

The 6–9 mark late-paper capstone reverts from 2025's "predict the spectra" inversion to classic structure determination: an unknown C4–C6 oxygenate (ester, ketone or amide) presented with MS (labelled base peak distinct from the parent ion), IR, 13C and a tabulated 1H NMR with separate integration and splitting columns; students draw, name and justify the structure from at least three spectra. Several models embed it in a reaction pathway.

Each model's own prediction

Claude Fable 5: MS/IR/13C/1H unknown embedded in reaction pathway, 7–9 marks (p 0.70)
Claude Opus 5: ester/amide with acylium base peak, 6–7 marks (p 0.66)
GPT-5.6 Sol: every structural feature linked to particular spectral data, 7–9 marks (p 0.69)
Gemini 3.1 Pro: branched ester, justify splitting and integration, 6–8 marks (p 0.85)
Grok 4.6: C5 oxygenate, carbonyl ~210 ppm, septet/doublet/singlet, 7–9 marks (p 0.78)
DeepSeek V4: ester C5H10O2 with isopropyl septet at δ4.9, 7–8 marks (p 0.65)

Marker-feedback lineage: Marking feedback 2021, 2022, 2023, 2024 (base-peak/parent-ion and integration/splitting errors)

In the practice paper: Q37

ICE-table Keq with the ADDED amount as the unknown 5 of 6 models expect this

chem-q2-keq-ice-added-species Section II 4–5 marks discriminator consensus 0.56

A gaseous equilibrium at a stated Keq in a fixed vessel is disturbed by adding one species; given the new equilibrium concentration of another species, calculate how much was added — the ICE table built in moles, converted to concentrations before substitution, with the added amount as the pronumeral. The 2021 Q31 / 2024 Q30 lineage.

Each model's own prediction

Claude Fable 5: p 0.60
Claude Opus 5: p 0.50
GPT-5.6 Sol: p 0.53
Grok 4.6: closed 1.00 L vessel variant, p 0.70
Gemini 3.1 Pro: simpler compute-Keq variant, p 0.80

Marker-feedback lineage: Marking feedback 2021, 2024

In the practice paper: Q25

Competing/selective precipitation: Q vs Ksp with a second-salt check 5 of 6 models expect this

chem-q3-competing-precipitation Section II 4–6 marks discriminator consensus 0.53

Solutions mixed to give two candidate precipitates (often sharing an ion): compute ionic products against data-sheet Ksp values, identify which salt precipitates first, then recompute the depleted ion to decide whether the second forms — or the common-ion molar-solubility variant for a non-1:1 salt.

Each model's own prediction

Claude Fable 5: p 0.55
Claude Opus 5: p 0.50
GPT-5.6 Sol: p 0.58
DeepSeek V4: Ba/Ca with Na2SO4, p 0.50
Grok 4.6: MC Q>Ksp variant, p 0.55

Marker-feedback lineage: Marking feedback 2020 Q33, 2022 Q35, 2025 Q32

In the practice paper: Q33

Back/multi-step titration on a consumer product, outlier titre, label-claim verdict 5 of 6 models expect this

chem-q4-back-titration-consumer-claim Section II 6–8 marks discriminator consensus 0.61

The big quantitative-analysis item: a consumer or industrial solid (antacid, aspirin, fertiliser, limestone, vinegar) analysed by back titration or standardisation-then-titration; four titres with one obvious outlier to exclude, an aliquot/dilution scaling step, closing with a judgement against the manufacturer's claim. The 2021 Q35 / 2023 Q32 / 2025 Q33 pattern.

Each model's own prediction

DeepSeek V4: CaCO3 in antacid, p 0.70
Claude Fable 5: p 0.65
Claude Opus 5: p 0.62
GPT-5.6 Sol: polyprotic variant, p 0.62
Grok 4.6: KHP standardisation + vinegar claim, p 0.58

Marker-feedback lineage: Marking feedback 2021 Q35, 2022 Q32, 2023 Q32, 2025 Q33

In the practice paper: Q31

Organic reaction pathway flow chart (alkene → alcohol → carbonyl → ester) 6 of 6 models expect this

chem-q5-reaction-pathway-flowchart Section II 4–8 marks discriminator consensus 0.57

A flow chart or reactivity list from an alkene or haloalkane through hydration/substitution, oxidation, and esterification; students draw structures A–D and state reagents and conditions. The nuance most models call: a tertiary alcohol that resists oxidation against a secondary one that yields a ketone (and Markovnikov vs anti-Markovnikov products).

Each model's own prediction

Claude Fable 5: p 0.70
Claude Opus 5: p 0.48
GPT-5.6 Sol: p 0.59
Gemini 3.1 Pro: p 0.85
Grok 4.6: branched alkene two-alcohol variant, p 0.55
DeepSeek V4: 1-bromopropane chain with distinguishing tests, p 0.55

Marker-feedback lineage: 2020 Q29, 2021 Q26, 2025 Q37 lineage

In the practice paper: Q35

Collision-theory explanation of a disturbance (Le Chatelier-only answers capped) 6 of 6 models expect this

chem-q6-collision-theory-disturbance Section II 3–6 marks discriminator consensus 0.56

A disturbance (species added/removed, or temperature change with an energy-profile diagram supplied) to a gaseous or coloured equilibrium; students must explain the response through collision frequency and the UNEQUAL forward/reverse rate changes — not just Le Chatelier — often with a concentration- or rate-time sketch.

Each model's own prediction

Claude Fable 5: p 0.65
Claude Opus 5: p 0.55
GPT-5.6 Sol: p 0.61
Gemini 3.1 Pro: multi-disturbance graph, p 0.75
Grok 4.6: sketch-other-species variant, p 0.52
DeepSeek V4: cooling exothermic NO2/N2O4, p 0.60

Marker-feedback lineage: 2019 Q25, 2022 Q23c, 2024 Q26 lineage; 2025 Q35 escalation

In the practice paper: Q24

pH of a conjugate salt via Ka↔Kb (Kw), ICE with justified approximation 4 of 6 models expect this

chem-q7-salt-hydrolysis-ph Section II 3–5 marks discriminator consensus 0.53

Calculate the pH of a salt of a weak acid or base (sodium ethanoate/acetate the favourite): write the hydrolysis equilibrium, convert Ka to Kb through Kw, run the ICE table with the small-x approximation explicitly justified, and finish through pOH.

Each model's own prediction

Claude Fable 5: p 0.55
Claude Opus 5: p 0.45
Grok 4.6: 0.20 M sodium ethanoate, p 0.60
DeepSeek V4: 0.15 M sodium acetate, p 0.50

Marker-feedback lineage: 2019 Q27, 2020 Q27, 2025 Q31b lineage

In the practice paper: Q23

AAS/colorimetry calibration curve with dilution factor and compliance judgement 5 of 6 models expect this

chem-q8-calibration-curve-dilution Section II 4–7 marks discriminator consensus 0.55

A calibration line (AAS, colorimetry or UV-vis) with a diluted sample: interpolate the absorbance, reverse the dilution, convert mol/L to mg/L via molar mass, and judge against a stated water-quality or discharge limit — returning to Section II after 2025 kept it MC-only.

Each model's own prediction

Claude Fable 5: p 0.60
Claude Opus 5: p 0.52
GPT-5.6 Sol: p 0.53
Grok 4.6: p 0.55
DeepSeek V4: Cu2+ wastewater, p 0.55

Marker-feedback lineage: 2019 Q29c, 2023 Q31, 2024 Q25 lineage

In the practice paper: Q27

Qualitative ion-testing sequence — including the flawed-procedure variant 6 of 6 models expect this

chem-q9-ion-testing-sequence Section II 3–7 marks discriminator consensus 0.55

Design or evaluate a precipitation/flame-test sequence for unknown ions. Three models specifically predict the harder variant: a stated sequence that returns a FALSE result because an early reagent precipitates more than one candidate — explain the failure and redesign, with balanced ionic equations and observations.

Each model's own prediction

Claude Fable 5: flawed-sequence variant, p 0.60
Claude Opus 5: flawed-sequence, p 0.50
GPT-5.6 Sol: redesign variant, p 0.57
Gemini 3.1 Pro: design, p 0.75
Grok 4.6: school-lab sequence, p 0.58
DeepSeek V4: two-of-six ions scheme, p 0.60

Marker-feedback lineage: 2021 Q30, 2023 Q30, 2024 Q27 lineage

In the practice paper: Q29

Calorimetry returns after its first absence in six years 3 of 6 models expect this

chem-q10-calorimetry-returns Section II 4–6 marks mid range consensus 0.58

Spirit-burner enthalpy of combustion of an alcohol: q = mcΔT, convert to ΔcH per mole, then explain why the experimental value sits far below the data-sheet value and justify an improvement. Opus's harder variant: the mass in q = mcΔT is not simply water (solution mass from density, non-4.18 specific heat, or CO2 mass loss).

Each model's own prediction

Claude Fable 5: p 0.60
Grok 4.6: p 0.62
Claude Opus 5: harder-mass variant, p 0.50

Marker-feedback lineage: 2019 Q23, 2022 Q29, 2023 Q25 lineage; absent 2025 (coverage gap)

In the practice paper: Q22

Conductometric titration graph explanation 4 of 6 models expect this

chem-q11-conductometric-titration Section II 3–6 marks mid range consensus 0.51

Explain the V-shaped or hockey-stick conductivity curve (Ba(OH)2 with H2SO4, or strong acid with weak base), naming the specific ions replaced and their relative mobilities, with balanced equations — rested in 2025.

Each model's own prediction

Claude Fable 5: p 0.45
GPT-5.6 Sol: p 0.38
Gemini 3.1 Pro: p 0.75
DeepSeek V4: Ba(OH)2/H2SO4 with calculation, p 0.55

Marker-feedback lineage: 2019 Q24, 2024 Q34 lineage

In the practice paper: Q26

IUPAC naming MC with wrong-end-numbering distractors 5 of 6 models expect this

chem-q12-iupac-naming-mc Section I 1 marks routine consensus 0.63

Multiple choice: preferred IUPAC name of a branched, substituted (often halogenated) chain. Distractor logic consistently predicted: numbering from the wrong end (higher locants), shorter parent chain, substituents out of alphabetical order — the 2022 "2-ethyl-3-chlorohexane" pattern.

Each model's own prediction

Claude Fable 5: p 0.70
Claude Opus 5: p 0.85
GPT-5.6 Sol: p 0.66
Grok 4.6: p 0.55
DeepSeek V4: p 0.60

In the practice paper: Q3

Watch list — worth having ready (6)

Gibbs free energy / ΔG spontaneity returns after resting in 2025 (fable 0.60, opus 0.42)
Weak-acid titration curve → pKa at half-equivalence (gpt-5.6-sol 0.58, opus 0.45)
Enthalpy of neutralisation strong-vs-weak contrast (fable 0.35, gpt-5.6-sol 0.34, opus 0.42)
Buffer question after two lean years (fable 0.55, gemini 0.65 as calculation, grok 0.48 qualitative)
Soap/micelle orientation — genuine coverage gap, examined once in seven years (fable only, 0.35)
Chemical synthesis is the panel's likely-rested call: 3 of 6 models rest it after it dominated 2025 (consensus P(examined) 0.65, the lowest of all 11 topics)

Where to spend your study time

How likely each topic is to appear this year.

Mod 8: Analysis of organic substances, spectroscopy 98% likely

Chance of a big question (4+ marks) here: 90%

Question types predicted here extended response ×7 multiple choice ×6 short answer ×3

What each model expects

DeepSeek V4: A 7–8 mark combined spectra question on an ester, requiring full justification of each peak, following the 2024 Q38 and 2025 Q36 pattern.
Claude Fable 5: A 7-mark combined-spectra structure determination returns in the final quarter of Section II, chained to a reaction pathway rather than a lone unknown.
Gemini 3.1 Pro: A 7-mark question in Section II demanding structure determination of a branched ester from 4 spectra, reversing the 2025 format.
GPT-5.6 Sol: A late-paper 7–9 mark question will return to determining an unknown structure from several complementary spectra, rather than merely predicting spectra for a supplied molecule.
Grok 4.6: A 7–9 mark late Section II unknown-compound item returns to deduce-structure-from-spectra after 2025’s predict-spectra reversal.
Claude Opus 5: The paper's single hardest item is again a 7-mark spectroscopy structure-determination question placed in the final five questions of Section II, reverting from 2025's predict-the-spectra inversion to the spectra-to-structure form.

Mod 5: Calculating Keq, solubility products 96% likely

Chance of a big question (4+ marks) here: 83%

Question types predicted here extended response ×9 multiple choice ×4 short answer ×3

What each model expects

DeepSeek V4: A 4–5 mark Ksp calculation from experimental precipitation data, requiring identification of the limiting reagent and equilibrium concentrations.
Claude Fable 5: A 4-mark ICE-table Keq calculation with an unknown added amount sits in the last third of Section II, alongside a Q-versus-Ksp precipitate decision question.
Gemini 3.1 Pro: A 5-mark ICE table calculation for a homogeneous gaseous equilibrium, pivoting away from 2025's heavy Ksp focus.
GPT-5.6 Sol: The main Module 5 calculation will combine selective precipitation with changing ion concentrations rather than ask only for a direct molar solubility.
Grok 4.6: A 4-mark ICE calculation in which a species is added after equilibrium, asking for the added amount, sits in mid Section II.
Claude Opus 5: A 4–6 mark solubility item requires a will-it-precipitate judgement using data-sheet Ksp values for two competing salts, not a single-salt Ksp substitution.

Mod 6: Titrations, buffers, quantitative analysis 96% likely

Chance of a big question (4+ marks) here: 84%

Question types predicted here extended response ×6 short answer ×5 practical analysis ×2 multiple choice ×2 stimulus based ×1

What each model expects

DeepSeek V4: A 6–7 mark back titration with an outlier, requiring brand identification from % purity, mirroring 2025 Q33 but with a different context.
Claude Fable 5: The big quantitative question of 2026 is a 6–8 mark multi-step titration with an outlier titre and a dilution factor, placed around Q32–Q35.
Gemini 3.1 Pro: A 5-mark conductometric titration graph analysis, pivoting away from the heavy volumetric back-titrations of 2025.
GPT-5.6 Sol: A 5–7 mark Section II titration calculation will combine standardisation, concordant titres and a dilution or back-titration step.
Grok 4.6: A forward (not back) multi-step titration of 6–7 marks, with an outlier to discard, replaces the 2021/2023/2025 back-titration slot.
Claude Opus 5: A 6–8 mark multi-step titration with a discardable outlier and a scaling factor ends in a verdict against a stated specification, mirroring the 2021, 2022, 2023 and 2025 shape rather than asking for a bare concentration.

Mod 6: pH, dissociation, calculations 94% likely

Chance of a big question (4+ marks) here: 74%

Question types predicted here extended response ×7 short answer ×4 multiple choice ×3

What each model expects

DeepSeek V4: A 4–5 mark pH calculation involving a buffer formed by partial neutralisation of a weak acid, requiring an ICE table and dilution correction.
Claude Fable 5: One excess-reagent pH calculation and one Kw-linked weak conjugate calculation appear as separate 4-markers in the middle of Section II.
Gemini 3.1 Pro: A complex 5-mark buffer pH calculation, testing the effect of adding a strong acid to an equimolar weak acid/conjugate base system.
GPT-5.6 Sol: The principal pH calculation will require an equilibrium or excess-reagent step before applying the logarithm.
Grok 4.6: A 4-mark ICE pH of a weak-acid salt or weak base, requiring Ka×Kb=Kw, appears in Section II.
Claude Opus 5: A 3–4 mark excess-reagent pH calculation returns, with the trap sitting in a diprotic acid or dibasic hydroxide making the neutralisation ratio 1:2 rather than 1:1.

Mod 7: Reactions of organic compounds, alcohols 94% likely

Chance of a big question (4+ marks) here: 77%

Question types predicted here extended response ×8 short answer ×3 multiple choice ×2 stimulus based ×1 practical analysis ×1

What each model expects

DeepSeek V4: A 6–7 mark reaction pathway question covering haloalkane to ester, requiring reagents, conditions, equations, and distinguishing tests.
Claude Fable 5: An organic pathway question demanding drawn structures plus a returning alcohol-combustion calorimetry calculation together carry 8–11 marks of Module 7.
Gemini 3.1 Pro: A 5-mark organic pathway flowchart requiring specific reagents, conditions (e.g., UV light, concentrated H2SO4), and correct structural isomers.
GPT-5.6 Sol: A Section II pathway will integrate hydration, alcohol classification and oxidation, with at least one condition written above the reaction arrow.
Grok 4.6: Alcohol combustion calorimetry plus an accuracy part returns in Section II after being absent in 2025.
Claude Opus 5: Calorimetry returns after its 2025 absence as a 4–5 mark q = mcdeltaT item whose discriminator is choosing the correct mass and specific heat capacity, not the arithmetic.

Mod 5: Static and dynamic equilibrium, Le Chatelier 94% likely

Chance of a big question (4+ marks) here: 75%

Question types predicted here extended response ×6 short answer ×5 multiple choice ×2 stimulus based ×1

What each model expects

DeepSeek V4: A 5–6 mark question explicitly demanding collision theory explanation for a temperature change, not Le Chatelier, with an energy profile diagram.
Claude Fable 5: 2026 pairs a collision-theory explanation question with a returning ΔG/spontaneity calculation — the entropy strand was MC-only in 2025 and is due a 3–5 mark slot.
Gemini 3.1 Pro: A 5-mark concentration-time graph interpretation requiring students to identify disturbances based on instantaneous vs gradual changes.
GPT-5.6 Sol: A graph-based perturbation question will require collision-theory reasoning, not merely a Le Chatelier direction statement.
Grok 4.6: Section II will demand a collision-theory account of a concentration or temperature disturbance and will not accept a bare Le Chatelier sentence.
Claude Opus 5: A 4–5 mark item again demands collision theory and Le Chatelier's principle in the same response, anchored to a supplied energy-profile diagram rather than to a bare equation.

Mod 8: Analysis of inorganic substances 92% likely

Chance of a big question (4+ marks) here: 72%

Question types predicted here practical analysis ×6 extended response ×5 short answer ×1 multiple choice ×1

What each model expects

DeepSeek V4: A 6–7 mark qualitative analysis scheme design, requiring a logical sequence of tests and evaluation of its ability to distinguish ions, with two balanced equations.
Claude Fable 5: A calibration-curve (AAS/colourimetry) calculation with a dilution factor returns to Section II at 4–7 marks, after being demoted to MC in 2025.
Gemini 3.1 Pro: A 5-mark experimental design question requiring a logical sequence of precipitation reactions to identify specific cations (e.g., Pb2+, Ba2+, Cu2+).
GPT-5.6 Sol: A practical-analysis question will require students to diagnose interference in an ion-testing sequence and propose a valid correction.
Grok 4.6: A 5-mark school-lab cation-plus-anion identification sequence returns to Section II after 2025 used only gravimetric-procedure critique.
Claude Opus 5: A 3–5 mark item asks students to evaluate a supplied ion-testing procedure that generates a false negative through test ordering, rather than to design a test sequence from scratch.

Mod 6: Properties of acids and bases 84% likely

Chance of a big question (4+ marks) here: 41%

Question types predicted here short answer ×6 multiple choice ×3 extended response ×3

What each model expects

DeepSeek V4: A 3–4 mark short-answer comparing acid–base models using a gas-phase reaction, targeting the Arrhenius limitation.
Claude Fable 5: The Arrhenius/Brønsted-Lowry model-classification question returns at 3–4 marks, three years after its 2023 outing.
Gemini 3.1 Pro: Relegated primarily to multiple choice, focusing on identifying conjugate acid-base pairs or amphiprotic species.
GPT-5.6 Sol: A 3–5 mark explanation will require acid–base equations and comparison of models or neutralisation energetics, not definitions alone.
Grok 4.6: A 4-mark Arrhenius-versus-Brønsted comparison with two equations, last seen in 2023 Q22, is the likely substantial item.
Claude Opus 5: A judgement-verb item on acid-base model limitations returns at 4–5 marks, the first since 2023 Q22 and the first using assess or evaluate since 2019 Q28.

Mod 7: Nomenclature, hydrocarbons, isomers 81% likely may rest

Chance of a big question (4+ marks) here: 47%

Question types predicted here short answer ×7 multiple choice ×5

What each model expects

DeepSeek V4: A 3–4 mark short-answer on drawing and naming isomers of C₅H₁₀, including geometric isomerism, targeting common nomenclature errors.
Claude Fable 5: Nomenclature stays MC-plus-2-marker; the near-certain Section II item is another intermolecular-forces trend explanation from a graph or table of two homologous series.
GPT-5.6 Sol: At least one item will target preferred IUPAC naming through an easily missed parent-chain or locant choice.
Grok 4.6: Section I opens or near-opens with an IUPAC naming or isomer-classification MC; a 2–4 mark draw-and-name sits at Q21–24.
Claude Opus 5: An isomer-classification or draw-all-isomers item returns to Section II after being absent in 2024 and 2025, worth 2–4 marks and demanding full expanded structures.

Mod 7: Organic acids/bases, esters, polymers 78% likely may rest

Chance of a big question (4+ marks) here: 59%

Question types predicted here short answer ×5 multiple choice ×2 extended response ×1

What each model expects

DeepSeek V4: A 3–4 mark short-answer on condensation polymerisation, requiring drawing the repeating unit and explaining biodegradability in terms of ester linkages.
Claude Fable 5: Polymers drop back to MC-plus-2-marker weight after 2025's Kevlar question; ester chemistry hides inside a pathway or yield calculation.
Gemini 3.1 Pro: A 4-mark question demanding the structural formula of a polyester or polyamide from its monomers.
Claude Opus 5: Polymers are rested from the 4-mark Kevlar-style treatment of 2025 back to a 1–3 mark monomer or repeat-unit task plus one multiple-choice item.

Mod 8: Chemical synthesis and design 65% likely may rest

Chance of a big question (4+ marks) here: 52%

Question types predicted here extended response ×3 short answer ×2 stimulus based ×1

What each model expects

DeepSeek V4: A 4–5 mark evaluation of an industrial equilibrium process, requiring discussion of rate, yield, and atom economy, with reference to specific conditions.
GPT-5.6 Sol: An industrial flow-chart evaluation will ask for targeted recycling or energy-recovery improvements rather than a generic list of synthesis factors.
Grok 4.6: A 6–8 mark school-laboratory organic synthesis design returns, because 2025 used industrial phosgene rather than the 2022 school-lab format.

How likely each topic is to appear. Open a topic for the question types to practise there.

Practise with the paper

Chemistry practice paper

100 marks · 37 questions

Every question is traceable to the consensus prediction behind it — open the web version and each question carries a “why this question” link into the evidence. All questions are original Intuition compositions in NESA style.

Read it on the web Download PDF Solutions (PDF)

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Published Aug 2026, before the exams. In November 2026 we score these predictions publicly against the real paper — per-model calibration and question-level hit rates, the same harness as the 2025 backtest. How we did it.

The near-certainties

Structure elucidation from combined spectra — the capstone

Organic reaction pathway flow chart (alkene → alcohol → carbonyl → ester)

Collision theory where Le Chatelier isn't enough

The big five (have these cold)

1. Structure elucidation from combined spectra — the capstone

2. The big titration — back-titration with an outlier

3. ICE-table Keq — with the added amount as the unknown

4. Collision theory where Le Chatelier isn't enough

5. The instrument calibration curve

Also on the radar

Where to spend less time

The honest fine print

Where to spend your study time

Practise with the paper

Chemistry practice paper

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