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IGCSE Chemistry Past Papers & Drilling (Paper 3): Ions, Neutralisation, Redox
TUTORZONE ORIGINAL DRILLING MOCK · CAMBRIDGE IGCSE CHEMISTRY (0620) PAPER 3
Written to the Cambridge 0620 syllabus: Paper 3 Theory (Core), 80 marks, 1 h 15 min, 50% (short-answer and structured); plus Paper 1 Multiple Choice (Core, 40 marks, 30%). This is a Paper 3 drilling mock: 6 questions for 80 marks with answers and techniques.
What is in IGCSE Chemistry (0620) Paper 3?
Direct answer: Paper 3 Theory (Core), 80 marks, 1 h 15 min, 50% (short-answer and structured).
Assessment at a glance (2027)
| Component | Content | Weighting | Duration |
|---|---|---|---|
| Paper 3 (Theory, Core) | Short-answer and structured, 80 marks | 50% | 1 h 15 min |
| Paper 1 (Multiple Choice, Core) | 40 four-option items, 40 marks | 30% | 45 min |
IGCSE Chemistry Paper 3 drilling technique: balance equations; ion electrons = protons ± charge; oxidation is loss, reduction is gain (OIL RIG); ionic compounds melt high because ionic bonds are strong.
How this paper was built
This is a TutorZone original drilling mock: the questions follow the Cambridge 0620 structure (Paper 3 Core, 80 marks, 50%) and the answers are our own, not Cambridge past papers or marking references.
Every numeric answer was recomputed programmatically.
Pacing
| Section | Marks | Suggested time | What to do first |
|---|---|---|---|
| Paper 3 (Theory, Core) | 50% | about 9 min per question | equations + explanation |
| Paper 1 (Multiple Choice, Core) | 30% | about 68 s per question | core content only |
How are oxidation and reduction defined by electrons?
Direct answer: oxidation is loss of electrons, reduction is gain (OIL RIG).
Paper 3: core theory drilling (6 questions, 80 marks)
Balance equations; remember OIL RIG for redox.
Question 1 (14 marks)
How many electrons are in Na+ and Cl-? Explain why Na+ is positive.
Question 2 (13 marks)
Calculate the Mr of H2O (H = 1, O = 16) and explain why ionic compounds have high melting points.
Question 3 (13 marks)
Write the neutralisation equation for hydrochloric acid and sodium hydroxide and state the pH of the product.
Question 4 (13 marks)
Define oxidation and reduction in terms of electron transfer.
Question 5 (13 marks)
Explain why aluminium is unreactive in practice despite being reactive.
Question 6 (14 marks)
State two differences between alkanes and alkenes in structure and reactions.
How many electrons are in Na+?
Direct answer: 10 (it loses one electron, so protons outnumber electrons).
Paper 3 answers
Question 1
Na+ has 10 electrons and Cl- has 18 (7); Na+ lost one electron so protons outnumber electrons, giving a positive charge (7).
Question 2
Mr = 2×1 + 16 = 18 (7); ionic compounds are held by strong electrostatic attraction (ionic bonds) needing much energy to break (6).
Question 3
HCl + NaOH -> NaCl + H2O (7); the product is a neutral salt solution, pH about 7 (6).
Question 4
Oxidation is loss of electrons (7); reduction is gain of electrons (6).
Question 5
Aluminium forms a thin, tough layer of aluminium oxide (7) that prevents further oxidation (protective layer) (6).
Question 6
Structure: alkanes have only single bonds (saturated) and alkenes have a C=C double bond (unsaturated) (7). Reactions: alkenes undergo addition (decolourising bromine water) while alkanes mainly burn (substitution) (7).
Which topics does this paper drill?
Direct answer: ion electron counts, ionic bonding and melting points, neutralisation, redox, protective layers, alkanes and alkenes.
Where these marks are usually lost
| Mistake | What it looks like | What it costs | Instead |
|---|---|---|---|
| Ion electron count | Na+ with 11 electrons | Na+ has 10 after losing one | 10 |
| Unbalanced equation | Miss coefficients | Check atoms on both sides | balanced |
| Redox reversed | Oxidation = gain | Oxidation = loss (OIL RIG) | loss |
How to use this paper
First drill: the full 1 h 15 min on all 6 questions with no references.
Mark it: check equation balancing and electron counts.
Second drill: redo three to seven days later, aiming to finish inside 1 hour.
What should I do after drilling this paper?
Direct answer: log unbalanced equations or wrong electron counts; redo in three to seven days; and drill Paper 4 (Extended theory).
FAQ
Is this a Cambridge past paper?
No. The questions and answers are TutorZone originals, not Cambridge past papers or marking references.
What is in IGCSE Chemistry Paper 3?
Theory (Core), 80 marks, 1 h 15 min, 50%, short-answer and structured questions.
How are oxidation and reduction defined by electrons?
Oxidation is loss of electrons; reduction is gain (OIL RIG).
Official references
| Resource | What to check |
|---|---|
| Cambridge IGCSE Chemistry 0620 page | Confirm the paper marks and times |
| https://www.tutorzone.com.hk/en-igcse-chemistry-0620-paper-1-mock-2027/ | IGCSE Chemistry Paper 1 drilling mock |
Related: practice area · IGCSE Chemistry Paper 2 drilling mock
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