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IGCSE Chemistry (0620) Paper 4 Mock: Moles, Concentration, Equations, Electrolysis, Bonding
TUTORZONE ORIGINAL MOCK PAPER · CAMBRIDGE IGCSE CHEMISTRY (0620) PAPER 4 (THEORY EXTENDED)
Written to the Cambridge 0620 syllabus (2026-2028): Extended candidates sit Paper 2 (multiple choice, 40 marks), Paper 4 (theory, 80 marks, 1 h 15 min) and Paper 5/6 (practical, 40 marks). This is a Paper 4 mock: 10 structured questions for 80 marks (calculation and concept) with answers.
What is in the IGCSE Chemistry (0620) exam?
Direct answer: Extended candidates sit three papers: Paper 2 (multiple choice, 40 marks, 45 min), Paper 4 (theory, 80 marks, 1 h 15 min) and Paper 5 or 6 (practical, 40 marks).
Assessment at a glance (2027)
| Component | Content | Weighting | Duration |
|---|---|---|---|
| Paper 4 (Theory, Extended) | Short-answer and structured, 80 marks | 80 marks | 1 h 15 min |
| Paper 2 (Multiple Choice, Extended) | 40 four-choice items, 40 marks | 40 marks | 45 min |
| Paper 6 (Alternative to Practical) | Practical-skills questions, 40 marks | 40 marks | 1 h |
Ten questions in 1 h 15 min is about 7 minutes each. For calculations write the formula (n = m/M, c = n/V), then substitute, then give the unit; for concepts give the definition and an example.
How this paper was built
This is a TutorZone original mock paper: the questions follow the Cambridge 0620 structure (Paper 4 theory, 80 marks, 1 h 15 min) and the answers are our own computations, not Cambridge past papers or marking references.
Every answer was recomputed programmatically.
Pacing
| Section | Marks | Suggested time | What to do first |
|---|---|---|---|
| Paper 4 (Theory, Extended) | 80 marks | about 7 min per question, 5 to check | formula first for calculations, definition for concepts |
| Paper 2 (Multiple Choice, Extended) | 40 marks | about 1 min per item | eliminate the clearly wrong options |
| Paper 6 (Alternative to Practical) | 40 marks | read data, record, analyse | accurate observation and conclusion |
How do I calculate moles?
Direct answer: n = m/M (moles = mass / molar mass). E.g. 12 g of Mg (24 g/mol) = 0.5 mol.
Paper 4: structured questions (10 questions, 80 marks)
All compulsory; aim for 70 minutes with 5 to check. Formula first for calculations, definition for concepts.
Question 1 (8 marks)
How many moles are in 12 g of magnesium (Mg, molar mass 24 g/mol)?
Question 2 (8 marks)
0.2 mol of solute is dissolved in 0.5 dm^3 of solution. Calculate the concentration.
Question 3 (8 marks)
What volume does 0.5 mol of gas occupy at room temperature? (molar volume = 24 dm^3/mol)
Question 4 (8 marks)
24 g of magnesium burns fully in oxygen to form magnesium oxide (MgO, molar mass 40 g/mol). Calculate the mass of magnesium oxide formed.
Question 5 (8 marks)
40 g of sodium hydroxide (NaOH, molar mass 40 g/mol) is dissolved to make 0.5 dm^3 of solution. Calculate the concentration.
Question 6 (8 marks)
Write a balanced equation for the burning of magnesium in oxygen.
Question 7 (8 marks)
Write the equation for the neutralisation of hydrochloric acid by sodium hydroxide, and name the salt formed.
Question 8 (8 marks)
When molten sodium chloride is electrolysed, what forms at the cathode and at the anode?
Question 9 (8 marks)
State the type of bonding in sodium chloride and in water, giving one reason for each.
Question 10 (8 marks)
Write a balanced equation for the complete combustion of methane (CH4).
How do I calculate concentration?
Direct answer: c = n/V (concentration = moles / volume), in mol/dm^3.
Paper 4 answers
Question 1
Use n = m/M (2): n = 12 / 24 = 0.5 mol (6).
Question 2
Use c = n/V (2): c = 0.2 / 0.5 = 0.4 mol/dm^3 (6).
Question 3
Volume = n x 24 (2): V = 0.5 x 24 = 12 dm^3 (6).
Question 4
Mg -> MgO is 1:1 (2): 24 g Mg = 1 mol (2), 1 mol MgO = 40 g (4).
Question 5
n = 40 / 40 = 1 mol (3): c = 1 / 0.5 = 2 mol/dm^3 (5).
Question 6
2Mg + O2 -> 2MgO (8). Balance the magnesium and oxygen atoms on both sides.
Question 7
HCl + NaOH -> NaCl + H2O (6); the salt is sodium chloride (2).
Question 8
Sodium (Na, the metal) forms at the cathode (4); chlorine (Cl2) forms at the anode (4). The cathode gains the metal, the anode gives the non-metal.
Question 9
(1) Sodium chloride: ionic – electron transfer between a metal (Na) and a non-metal (Cl), forming oppositely charged ions (4). (2) Water: covalent – shared electrons between non-metals (H and O) (4).
Question 10
CH4 + 2O2 -> CO2 + 2H2O (8). Complete combustion gives carbon dioxide and water.
What does electrolysing molten sodium chloride give?
Direct answer: sodium (Na) at the cathode and chlorine (Cl2) at the anode.
Where these marks are usually lost
| Mistake | What it looks like | What it costs | Instead |
|---|---|---|---|
| Wrong molar mass | Taking Mg as 12 g/mol | Read the molar mass from the periodic table | Mg is 24 g/mol |
| Unbalanced equation | Writing Mg + O2 -> MgO | Balance the atoms on both sides | 2Mg + O2 -> 2MgO |
| Swapped electrodes | Chlorine at the cathode | Cathode gains the metal, anode the non-metal | Na at the cathode, Cl2 at the anode |
How to use this paper
First sit: the full 1 h 15 min on all 10 questions with no references.
Mark it: check formula, substitution, unit and definitions.
Second sit: redo three to seven days later, aiming to finish inside 1 hour.
What should I do after finishing this paper?
Direct answer: log errors on moles, concentration and balancing; redo in three to seven days; and drill Paper 2 multiple choice and Paper 6 practical skills.
FAQ
Is this a Cambridge paper?
No. The questions and answers are TutorZone originals, not Cambridge past papers or marking references.
How many papers does IGCSE Chemistry have?
Extended candidates sit three: Paper 2 (MC 40), Paper 4 (theory 80) and Paper 5 or 6 (practical 40).
What is the molar volume at room temperature?
About 24 dm^3/mol.
Official references
| Resource | What to check |
|---|---|
| Cambridge IGCSE Chemistry 0620 syllabus (2026-2028) | Confirm the Paper 2/4/6 marks and times |
| https://www.tutorzone.com.hk/en-igcse-physics-0625-paper-4-mock-2027/ | IGCSE Physics (0625) Paper 4 mock |
Related: practice area · IGCSE Physics Paper 4 mock · IGCSE Chemistry Paper 6 drilling mock · IGCSE English 0500 mock
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