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HKDSE Chemistry Paper 1 Mock Paper (2027): 20 MC and 6 Section B Questions with Answers
TUTORZONE ORIGINAL MOCK PAPER · HKDSE CHEMISTRY PAPER 1
Written to the HKEAA 2027 framework: Paper 1 covers the Compulsory Part, 60% of the subject, 2 hours 30 minutes, with Section A multiple-choice at 18% of the subject mark and Section B (short, structured and essay questions) at 42%, all compulsory. This paper has 20 MC items and 6 Section B questions with answers and mark allocation.
What is in HKDSE Chemistry Paper 1?
Direct answer: Paper 1 covers the Compulsory Part, is 60% of the subject and lasts 2 hours 30 minutes, with every question compulsory. Section A is multiple-choice and takes 18% of the subject mark; Section B – short questions, structured questions and an essay – takes the remaining 42%. The Elective Part is Paper 2 (20%) and SBA is 20%.
Assessment at a glance (2027)
| Component | Content | Weighting | Duration |
|---|---|---|---|
| Section A (multiple-choice) | Compulsory Part; 18% of the subject mark | 18%（全科） | 35-40 min |
| Section B (short, structured, essay) | Compulsory Part; 42% of the subject mark, ending with an essay question | 42%（全科） | 100-110 min |
| Paper 1 total | All questions compulsory; Paper 2 (Electives) is another 20% in 1 hour of structured questions, plus SBA 20% for school candidates | 60% | 2 h 30 min |
Cut the 150 minutes as 38 for Section A, 105 for Section B and 7 to check. Section B marks sit in three steps: write the equation with state symbols, work out the moles, then convert to the unit asked for. Answers alone lose most of the credit.
How this paper was built
This is a TutorZone original mock paper: the questions follow the 2027 framework’s structure (Section A MC at 18% of the subject mark, Section B at 42%, all compulsory) and the answers and mark allocation are our own, not HKEAA past papers or marking references.
HKEAA publishes no fixed question count for Paper 1, so this paper sets its own: 20 MC items and 6 Section B questions, one of them an essay question. Every numeric answer was recomputed programmatically.
Pacing
| Section | Marks | Suggested time | What to do first |
|---|---|---|---|
| Section A (multiple-choice) | 18%（全科） | 35-40 min | Moles first on any calculation; definitions on concepts |
| Section B (short, structured, essay) | 42%（全科） | 100-110 min | Equations with state symbols; never drop units |
| Paper 1 total | 60% | 150 min (about 38 for A and 105 for B) | Keep 12-15 minutes for the essay |
How should the 150 minutes be split?
Direct answer: about 38 minutes on Section A, 105 on Section B and 7 to check. Section B marks follow equation with state symbols, then moles, then the unit asked for; give the essay 12-15 minutes rather than the last five.
Section A: multiple-choice (20 questions, 18% of the subject mark)
Aim for 35-40 minutes. Moles first on calculations; definitions on concepts.
Question 1
What is the mass of 0.5 mol of carbon dioxide? (C = 12, O = 16)
A. 11 gB. 44 gC. 22 gD. 30 g
Question 2
What is the mass of 3.01 × 10²³ water molecules? (H₂O = 18 g mol⁻¹)
A. 0.5 gB. 18 gC. 36 gD. 9 g
Question 3
0.2 mol of solute is dissolved to make 0.5 dm³ of solution. Find the concentration.
A. 0.25 mol dm⁻³B. 2.5 mol dm⁻³C. 0.1 mol dm⁻³D. 0.4 mol dm⁻³
Question 4
25 cm³ of 0.4 mol dm⁻³ solution is diluted to 100 cm³. Find the new concentration.
A. 1.6 mol dm⁻³B. 0.025 mol dm⁻³C. 0.1 mol dm⁻³D. 0.2 mol dm⁻³
Question 5
25.0 cm³ of NaOH is neutralised by 20.0 cm³ of 0.10 mol dm⁻³ HCl. Find the concentration of the NaOH.
A. 0.10 mol dm⁻³B. 0.08 mol dm⁻³C. 0.125 mol dm⁻³D. 0.05 mol dm⁻³
Question 6
How many moles are in 4.8 dm³ of hydrogen at room temperature and pressure? (Molar volume 24 dm³ mol⁻¹)
A. 0.05 molB. 0.2 molC. 0.24 molD. 5 mol
Question 7
4 mol of hydrogen burns completely (2H₂ + O₂ → 2H₂O). What mass of water is formed?
A. 144 gB. 18 gC. 36 gD. 72 g
Question 8
If 1 mol of a fuel releases 890 kJ on complete combustion, how much energy does 0.25 mol release?
A. 222.5 kJB. 89 kJC. 445 kJD. 890 kJ
Question 9
In the electrolysis of copper(II) sulphate solution, what mass of copper is deposited at the cathode per 2 mol of electrons? (Cu = 63.5)
A. 31.75 gB. 127 gC. 63.5 gD. 12.7 g
Question 10
What is the pH of 0.001 mol dm⁻³ hydrochloric acid?
A. 1B. 13C. 11D. 3
Question 11
What is the pH of 0.01 mol dm⁻³ sodium hydroxide solution?
A. 13B. 12C. 2D. 10
Question 12
What is the oxidation number of manganese in potassium manganate(VII), KMnO₄?
A. +7B. +2C. +6D. +4
Question 13
Which of the following describes an oxidising agent?
A. 它使其他物質被氧化，自身被還原B. 它使其他物質被還原，自身被氧化C. 它的氧化數上升D. 它在反應中失去電子
Question 14
Across a period from left to right, how does atomic radius change?
A. 不變B. 先增後減C. 逐漸減小D. 逐漸增大
Question 15
Solid sodium chloride does not conduct, but molten sodium chloride does. Why?
A. 熔融時產生自由電子B. 熔融時分子變小C. 熔融時離子可自由移動D. 熔融時變為共價化合物
Question 16
Ethanol heated with concentrated sulphuric acid at about 170 °C mainly gives what?
A. 乙烯B. 乙烷C. 乙酸D. 乙醛
Question 17
A carboxylic acid reacts with an alcohol under acid catalysis. Which functional group is formed?
A. 羥基（醇）B. 氨基（胺）C. 酯基（酯）D. 醛基（醛）
Question 18
Nylon 6,6 belongs to which class of polymer?
A. 天然聚合物B. 縮合聚合物C. 加成聚合物D. 無機聚合物
Question 19
Why does a catalyst speed up a reaction?
A. 改變反應的平衡常數B. 提高反應的活化能C. 降低反應的活化能D. 增加生成物的能量
Question 20
For N₂(g) + 3H₂(g) ⇌ 2NH₃(g), what is the effect of increasing the pressure?
A. 氨的產量減少B. 平衡不移動C. 平衡向左移動D. 平衡向右移動，氨的產量增加
Section B: short, structured and essay questions (6 questions, 42% of the subject mark)
Aim for 100-110 minutes. Equations need state symbols, numbers need units; keep 12-15 minutes for the essay.
Question 1 (7 marks)
6.5 g of zinc reacts completely with excess dilute hydrochloric acid (Zn + 2HCl → ZnCl₂ + H₂). (a) Find the moles of zinc; (b) find the moles of hydrogen formed; (c) find the volume of hydrogen at room temperature and pressure (molar volume 24 dm³ mol⁻¹); (d) find the moles of HCl needed.
Question 2 (8 marks)
25.0 cm³ of sodium hydroxide solution is titrated with 0.100 mol dm⁻³ sulphuric acid, of which 12.5 cm³ is used on average. (a) Write the ionic equation; (b) find the moles of sulphuric acid used; (c) find the concentration of the sodium hydroxide.
Question 3 (7 marks)
Burning 0.5 g of methanol raises the temperature of 200 g of water by 8.0 °C (specific heat capacity of water 4.2 J g⁻¹ °C⁻¹). (a) Find the energy absorbed by the water; (b) find the energy released per gram of methanol; (c) find the enthalpy change of combustion in kJ mol⁻¹ (methanol = 32 g mol⁻¹).
Question 4 (7 marks)
A current of 2.0 A passes through copper(II) sulphate solution for 30 minutes. (a) Find the charge passed; (b) find the moles of copper deposited (1 mol of electrons = 96 500 C); (c) find the mass of copper deposited (Cu = 63.5); (d) what happens to the mass if the current is raised to 4.0 A?
Question 5 (8 marks)
Ethanol can be converted into several organic compounds. (a) Name the reaction and the product when ethanol is heated with concentrated sulphuric acid to about 170 °C; (b) name the product of reacting (a) with hydrogen bromide; (c) name the product and the reaction type when (a) undergoes addition polymerisation.
Question 6 (8 marks) essay question
Discuss why heavy metal ions in industrial effluent must be treated, and describe two feasible treatment methods with their chemistry.
Where are the answers, and do they show the steps?
Direct answer: each question is followed by an answer-and-marks block giving the equation, the moles, the answer with units and the marks each step earns (the first Section B question: 2 marks for the moles, 2 for the gas volume, 2 for the acid), plus the usual losses.
Section A answers and explanations
Question 1
Answer: C (22 g) Molar mass = 44 g mol⁻¹; 0.5 × 44 = 22 g.
Question 2
Answer: D (9 g) Moles = 3.01 × 10²³ ÷ 6.02 × 10²³ = 0.5 mol; 0.5 × 18 = 9 g.
Question 3
Answer: D (0.4 mol dm⁻³) Concentration = moles ÷ volume = 0.2 ÷ 0.5.
Question 4
Answer: C (0.1 mol dm⁻³) Diluted four-fold: 0.4 ÷ 4 = 0.1 (moles unchanged).
Question 5
Answer: B (0.08 mol dm⁻³) A 1:1 reaction: 0.10 × 20 ÷ 25 = 0.08.
Question 6
Answer: B (0.2 mol) Moles = volume ÷ molar volume = 4.8 ÷ 24.
Question 7
Answer: D (72 g) Mole ratio 2:2, so 4 mol of water forms; 4 × 18 = 72 g.
Question 8
Answer: A (222.5 kJ) Energy is proportional to moles: 890 × 0.25.
Question 9
Answer: C (63.5 g) Cu²⁺ + 2e⁻ → Cu: 2 mol of electrons give 1 mol of copper.
Question 10
Answer: D (3) pH = −log(0.001) = 3 (a strong acid ionises completely).
Question 11
Answer: B (12) pOH = −log(0.01) = 2, so pH = 14 − 2 = 12.
Question 12
Answer: A (+7) K⁺ is +1 and four O give −8, so Mn is +7.
Question 13
Answer: A (它使其他物質被氧化，自身被還原) An oxidising agent accepts electrons, is itself reduced, and oxidises the other species.
Question 14
Answer: C (逐漸減小) Nuclear charge rises while the number of shells stays the same, so the radius falls.
Question 15
Answer: C (熔融時離子可自由移動) An ionic compound conducts through mobile ions; in the solid the ions are locked in the lattice.
Question 16
Answer: A (乙烯) This is dehydration of ethanol, giving ethene and water.
Question 17
Answer: C (酯基（酯）) This is esterification, giving an ester and water.
Question 18
Answer: B (縮合聚合物) It forms from a diamine and a diacid with the loss of a small molecule (water).
Question 19
Answer: C (降低反應的活化能) It provides a route of lower activation energy; the equilibrium constant is unchanged.
Question 20
Answer: D (平衡向右移動，氨的產量增加) Four moles of gas on the left against two on the right, so pressure favours the side with fewer gas moles.
Section B answers and mark allocation
Question 1
(a) n = 6.5 ÷ 65 = 0.1 mol (2 marks); (b) ratio 1:1, so 0.1 mol of H₂ (1 mark); (c) V = 0.1 × 24 = 2.4 dm³ (2 marks); (d) 2 × 0.1 = 0.2 mol of HCl (2 marks).
Question 2
(a) H⁺ + OH⁻ → H₂O (2 marks); (b) n = 0.100 × 12.5/1000 = 1.25 × 10⁻³ mol (3 marks); (c) each H₂SO₄ gives two H⁺, so n(NaOH) = 2.5 × 10⁻³ mol and the concentration is 2.5 × 10⁻³ ÷ 0.025 = 0.100 mol dm⁻³ (3 marks).
Question 3
(a) Q = mcΔT = 200 × 4.2 × 8.0 = 6 720 J (2 marks); (b) 6 720 ÷ 0.5 = 13 440 J g⁻¹ (2 marks); (c) 13 440 × 32 = 430 080 J ≈ 430 kJ mol⁻¹ (3 marks).
Question 4
(a) Q = It = 2.0 × 1800 = 3 600 C (2 marks); (b) 3 600 ÷ 96 500 ÷ 2 = 1.87 × 10⁻² mol (3 marks); (c) 1.87 × 10⁻² × 63.5 ≈ 1.18 g (1 mark); (d) doubling the current doubles the charge in the same time, so roughly double the copper (1 mark).
Question 5
(a) Dehydration (1 mark) giving ethene (1 mark); (b) bromoethane (2 marks; ethene + HBr → CH₃CH₂Br is an addition reaction); (c) poly(ethene) (2 marks) by addition polymerisation (2 marks).
Question 6
Why (2 marks): heavy metal ions are not biodegradable and accumulate along food chains (bioaccumulation), damaging the nervous system and kidneys, and contaminated water and soil are very hard to restore.
Method 1 (3 marks): add sodium hydroxide or lime so the metal ions form insoluble hydroxide precipitates (Cu²⁺ + 2OH⁻ → Cu(OH)₂↓), then filter off the sludge.
Method 2 (3 marks): ion exchange – pass the effluent through an ion-exchange resin so the metal ions are exchanged and retained, and the resin can be regenerated to recover the metal; or electrolytic recovery, reducing the metal at the cathode.
Marks go per point, reason and example, so every claim needs its chemistry.
Where are Paper 1 marks most easily lost?
Direct answer: three places – equations with no state symbols or unbalanced, treating a volume as a number of moles, and unit conversion between cm³ and dm³. Essays that say only “it pollutes the environment” without the chemistry earn no points either.
Where these marks are usually lost
| Mistake | What it looks like | What it costs | Instead |
|---|---|---|---|
| Equations without state symbols | Formula only | Equation marks go; the state also decides how you use molar volume | Write (s)(l)(g)(aq) and balance the coefficients |
| Confusing moles with concentration | Treating a volume as a number of moles | Titration and gas calculations are where Section B marks live and die | Write n = cV or n = V/24 before substituting |
| Units and significant figures | Bare numbers | Wrong or missing units and accuracy lose marks | Convert dm³/cm³ early and state units in the answer |
| Essays without chemistry | Talking only about pollution | Essays are marked per point, reason and example | Every point needs its chemical process or equation |
How to use this paper
First sit: no references, the full 150 minutes, no textbook or periodic table.
Mark it: tick equation, moles, answer and units for every part, and tag each error as conceptual or arithmetic.
Second sit: redo it three to seven days later aiming for every Section B step written out, not just a right answer.
What should I do after this paper?
Direct answer: sort the losses into conceptual and arithmetic; drill past-paper questions by topic (mole calculations, acid-base titration, energetics, electrolysis, organic chemistry); then redo Section B three to seven days later with every step written out.
FAQ
Is this an HKEAA paper?
No. The questions, answers and mark allocation are TutorZone originals; only the framework figures (60%, 18%, 42%, 150 minutes) come from the HKEAA 2027 assessment framework.
How many questions does Paper 1 have?
HKEAA publishes no fixed count. This paper sets its own: 20 MC items and 6 Section B questions, proportioned to the 18/42 split.
What about Paper 2 and SBA?
Paper 2 covers the Elective Part: 20% in 1 hour of structured questions. SBA is 20% and compulsory for school candidates.
Official references
| Resource | What to check |
|---|---|
| HKEAA 2027 HKDSE Chemistry Assessment Framework | Confirm Paper 1’s 60%, 2 h 30 min, Section A 18% and Section B 42% |
| https://www.tutorzone.com.hk/en-dse-chemistry-paper-1-drill-guide/ | Paper 1 drilling guide: pacing and structured-question writing |
| https://www.tutorzone.com.hk/en-dse-chemistry-paper-2-electives-drill-guide/ | Paper 2 (Electives) drilling guide |
Related: practice area · Paper 2 electives guide · Physics Paper 1 mock
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