Cambridge IGCSE Chemistry 0620/12 is the May/June 2026 Paper 1 (Core Multiple Choice), variant 2. It lasts 45 minutes, has 40 questions worth one mark each (40 marks in total) and is sat by every Core candidate. Every syllabus area appeared, with seven questions each on particles and bonding and on organic chemistry, and only one full reacting-mass calculation. The mark scheme is an answer key, so this guide gives every answer with the topic it tested and the chemistry behind it. The paper and its mark scheme are free on the Tutopiya Learning Portal.

For an overview of all six 0620 papers from this series, see IGCSE Chemistry 0620 May/June 2026 past papers: what came up and how it was marked.

0620/12 at a glance

Syllabus area	Questions	Number of questions
States of matter, atoms and bonding	1–7	7
Stoichiometry	8–9	2
Electrochemistry	10–12	3
Chemical energetics, rates and reversible reactions	13–15	3
Acids, bases and salts	16–18	3
The Periodic Table	19–22	4
Metals	23, 25–27	4
Chemistry of the environment	24, 28–30	4
Organic chemistry	31–37	7
Experimental techniques and chemical analysis	38–40	3
Total		40

Answer key and topic for every question

Question	What it tested	Answer
1	Why bromine vapour spreads through a gas jar (diffusion)	B
2	Relative charge and relative mass of an electron	A
3	Protons, neutrons and electrons in a lithium-7 atom	A
4	Dot-and-cross diagram for a Group I–Group VII ionic bond	C
5	Number of shared electrons in an ammonia molecule	C
6	Graphite use that depends on sliding layers	D
7	Molecular formula of phosphoric acid from its structure	C
8	Masses of oxygen used and water made burning methane	D
9	Which units are units of concentration	C
10	Electrodes and electrolyte for silver-plating nickel	B
11	What an insoluble binary compound that electrolyses must be	A
12	How a hydrogen fuel cell powers a car	D
13	Definition of an exothermic reaction	B
14	Gas volume–time graph when surface area increases	B
15	Meaning of the reversible reaction symbol	D
16	Gas released when lime meets ammonium salts	A
17	Indicator colour, pH and H⁺ concentration of a strong acid	C
18	Method for preparing solid magnesium sulfate	C
19	Charge on a strontium ion	B
20	Identifying three Group I metals from density and melting point	A
21	Predicting properties of fluorine from Group VII trends	D
22	A typical property of cobalt as a transition element	A
23	Property that suits aluminium to food containers	D
24	Acid and alkali that make a salt useful as a fertiliser	B
25	Reaction with dilute acid and thermal conductivity of zinc	D
26	Comparing rusting of four nails in different conditions	A
27	Ore of aluminium and how it is extracted	B
28	Substances found in natural water	A
29	Source and effect of an air pollutant	B
30	Neptune’s atmosphere compared with Earth’s	C
31	Which organic compounds are hydrocarbons	C
32	Uses of gas oil and naphtha	C
33	Which fuels are fossil fuels	D
34	Formula of a compound that decolourises bromine water	D
35	Manufacture and combustion of ethanol	B
36	Other product when ethanoic acid reacts with potassium hydroxide	D
37	How poly(ethene) forms, and from what	B
38	Steps to separate sand from salt	B
39	The test for chlorine gas	A
40	Flame colour of a compound identified by aqueous ammonia	A

What the paper tested, topic by topic

States of matter, atoms and bonding (Questions 1–7)

• Diffusion (Q1): the colour spreads evenly because bromine particles move from high to low concentration. The other options talk about density, speed or mass, none of which explains the even colour.
• The electron (Q2): relative charge −1 and a relative mass of 1/1840. Row C has the right mass with the wrong charge, and row D has the right charge with the mass of a proton.
• Lithium-7 (Q3): proton number 3 and nucleon number 7, so the nucleus holds 3 protons and 7 − 3 = 4 neutrons, with 3 electrons in the shells. Options C and D put electrons in the nucleus.
• Ionic bonding (Q4): the Group I atom M loses its electron to become M⁺ and the Group VII atom N gains one to become N⁻ with a full outer shell. Option A has the charges the wrong way round, and B and D show shared electrons, which is covalent bonding.
• Ammonia (Q5): three N–H bonds, each a shared pair of electrons, so 6 shared electrons. The lone pair on nitrogen is not shared, so 8 is wrong.
• Graphite (Q6): lubricant is the use that relies on layers sliding. Electrodes depend on conductivity, and cutting tools and jewellery are uses of diamond.
• Phosphoric acid (Q7): count the atoms on the displayed structure: 3 H, 1 P and 4 O, giving H₃PO₄.

Stoichiometry (Questions 8–9)

• Reacting masses (Q8): 160 g ÷ 16 = 10 mol of methane. The equation needs 2 mol of oxygen per mole of methane, so 20 mol × 32 = 640 g of oxygen, and it makes 2 mol of water per mole, so 20 mol × 18 = 360 g of water. Options A and C use 180 g of water, which is what you get if you forget the 2 in front of H₂O.
• Concentration units (Q9): g/dm³ and mol/dm³. The other two are units of molar volume and molar mass.

Electrochemistry (Questions 10–12)

• Electroplating (Q10): the object being plated is the cathode, so nickel is the cathode, silver is the anode and the electrolyte must contain silver ions (aqueous silver nitrate). Option A swaps the electrodes.
• Electrolysis (Q11): an insoluble compound cannot be electrolysed as a solution, and covalent compounds do not conduct, so X must be a molten ionic compound.
• Fuel cells (Q12): the cell turns hydrogen and oxygen into electricity, which drives an electric motor. The hydrogen comes from a fuel tank, not the air, and the only product is water.

Chemical energetics, rates and reversible reactions (Questions 13–15)

• Exothermic (Q13): thermal energy goes out to the surroundings, so their temperature rises. Each wrong option mismatches the direction of transfer with the temperature change.
• Surface area graph (Q14): a larger surface area gives a steeper start for Y, but the same amounts of reactants give the same final volume, so both curves level off at the same height. Graph A has Y making more gas, which a change in surface area cannot do.
• The ⇌ symbol (Q15): it shows the reaction is reversible.

Acids, bases and salts (Questions 16–18)

• Lime and ammonium salts (Q16): a base reacting with an ammonium salt releases ammonia, which is why farmers do not add them together.
• Universal indicator (Q17): a strong acid turns it red, has pH 1 and a high hydrogen ion concentration. Row B pairs a weak acid with blue and pH 6, and row A gives a strong alkali a high H⁺ concentration.
• Making a soluble salt from an insoluble base (Q18): add excess magnesium oxide so all the acid is used up, filter off the unreacted oxide, then evaporate the filtrate. Options B and D treat magnesium sulfate as a precipitate, but it is soluble.

The Periodic Table (Questions 19–22)

• Strontium (Q19): it is in Group II, so it forms 2+ ions.
• Group I trends (Q20): lithium has a lower density than sodium, and sodium has a higher melting point than potassium, so P, Q and R are lithium, sodium and potassium.
• Fluorine (Q21): it forms F₂ molecules and, going up Group VII, density decreases, so fluorine is less dense than chlorine. It is a gas, not a solid, and iodine is less reactive so it cannot displace fluorine.
• Transition elements (Q22): they form coloured compounds. They are good conductors with high density and high melting points, which rules out B, C and D.

Metals (Questions 23 and 25–27)

• Aluminium food containers (Q23): the question asks which properties make aluminium useful for food containers, not which properties aluminium has. The keyed row (D) ticks only high resistance to corrosion, the property the syllabus links to food containers. Aluminium does have a low density, but the syllabus links that property to aircraft, and electrical conductivity has nothing to do with holding food. Learn the use–property pairs as the syllabus states them.
• Zinc (Q25): it reacts with dilute acid and is a good thermal conductor, like most metals above hydrogen in the reactivity series.
• Rusting (Q26): nail W is iron with wet cotton wool (air and water), nail X is iron coated in grease, nail Y is stainless steel and nail Z is iron in damp air. Grease keeps out air and water, so W rusts more than X. Option B is the trap: Z is exposed to damp air and will rust, while greased X is protected.
• Aluminium extraction (Q27): bauxite, by electrolysis. Aluminium is too reactive to be reduced by carbon, and hematite is the ore of iron.

Chemistry of the environment (Questions 24 and 28–30)

• Fertiliser salt (Q24): ammonia and nitric acid make ammonium nitrate, where both the ammonium and nitrate ions supply nitrogen. Sodium and chloride ions are not plant nutrients.
• Natural water (Q28): some dissolved metal compounds supply essential minerals. Dissolved oxygen is needed by aquatic life, phosphates cause oxygen depletion through eutrophication, and most plastics do not break down.
• Air pollutants (Q29): methane from decomposing vegetation adds to global warming. Carbon monoxide comes from incomplete combustion, nitrogen dioxide from car engines, and sulfur dioxide causes acid rain rather than global warming.
• Neptune’s atmosphere (Q30): a data table gave hydrogen 80%, helium 18%, methane 1.5% and other gases 0.5%. Earth’s air contains only a trace of hydrogen, so there is less hydrogen on Earth. Option A fails because oxygen is about 21% of Earth’s air, more than the 18% helium on Neptune.

Organic chemistry (Questions 31–37)

• Hydrocarbons (Q31): only ethane and ethene contain just carbon and hydrogen. Ethanol and ethanoic acid contain oxygen.
• Fractions (Q32): gas oil is diesel engine fuel and naphtha is a feedstock for making chemicals. Jet fuel is kerosene and road surfaces use bitumen.
• Fossil fuels (Q33): petroleum and natural gas. Ethanol and hydrogen can be made without fossil sources.
• Bromine water (Q34): C₄H₈ fits CₙH₂ₙ, the alkene formula, so it has a C=C bond and decolourises bromine water. C₄H₁₀ is an alkane.
• Ethanol (Q35): it is made from ethene and steam at about 300 °C and burns to carbon dioxide and water. Fermentation runs at a much lower temperature than 55 °C, and ethanol has no C=C bond.
• Neutralisation (Q36): acid + alkali gives a salt and water only. Hydrogen comes from acids with metals, and carbon dioxide from acids with carbonates.
• Poly(ethene) (Q37): the repeating –CH₂– chain is made by addition polymerisation of an alkene. Cracking breaks large alkanes into smaller molecules.

Experimental techniques and chemical analysis (Questions 38–40)

• Sand and salt (Q38): dissolve the salt in a solvent such as water, then filter off the sand. Distillation is not needed to get the sand.
• Chlorine (Q39): it bleaches damp litmus paper. Turning limewater cloudy is the test for carbon dioxide, and turning red litmus blue is the test for ammonia.
• Copper(II) ions (Q40): a light blue precipitate with aqueous ammonia that dissolves in excess identifies Cu²⁺, and copper gives a blue-green flame. Lilac is potassium, red is lithium and yellow is sodium.

Where the marks are on 0620/12

• Organic chemistry and particles, atoms and bonding carried 7 marks each, 14 of the 40 between them. Both are mostly recall, so they are the quickest marks to secure.
• The Periodic Table, metals and the environment had four questions each, 12 marks together.
• Only one question was a full calculation: the methane reacting masses in Q8. Q3 (neutrons from nucleon number), Q5 (counting shared electrons) and Q7 (counting atoms) needed simple counting.
• Two questions needed you to read data: the gas volume–time graphs in Q14 and the Neptune composition table in Q30. Q26 needed you to interpret a diagram of four test tubes.
• Five questions asked you to pick a pair or set of correct statements (Q9, Q21, Q33, Q35 and Q38), and many others were table rows with two or three columns. Every part of the chosen row or pair has to be right, so check each part separately.

How to self-mark 0620/12

1. Mark against the key only. Each question is worth one mark and there are no partial marks, so a row that is half right scores nothing.
2. Tag every wrong answer by topic, using the syllabus areas in the table above. Three wrong in one area tells you where to revise.
3. Tag it by reason as well:
   • Knowledge: you did not know the fact, for example the uses of gas oil and naphtha (Q32) or the flame colour of copper (Q40).
   • Misread: you knew the chemistry but missed a detail, such as reading “more rusting in X than Z” the wrong way round in Q26.
   • Calculation: you set up the working wrongly, for example forgetting the 2 in front of H₂O in Q8.
4. Fix knowledge gaps first. Most questions on this paper test recall, so a list of the facts you missed is your revision plan.
5. Redo every wrong question a week later without looking at the key, to check the fix has stuck.

Sit 0620/12 as a timed mock

The paper allows 45 minutes for 40 questions, about one minute each. Use two passes: answer everything you are sure of first, flag anything slow, then come back.

Block	Questions	Time
First pass, Questions 1–20	20	17 minutes
First pass, Questions 21–40	20	17 minutes
Second pass: flagged questions and the Q8 calculation	–	8 minutes
Final check: one answer per question on the answer sheet	–	3 minutes

Never leave a question blank. There is nothing to lose by making your best choice after ruling out the options you know are wrong.

Other May/June 2026 0620 papers

• 0620 Paper 22 (Extended Multiple Choice)
• 0620 Paper 32 (Core Theory)
• 0620 Paper 42 (Extended Theory)
• 0620 Paper 52 (Practical Test)
• 0620 Paper 62 (Alternative to Practical)

Practise and download

• Download 0620/12 and its mark scheme on the Learning Portal →
• All 0620 May/June 2026 papers: overview and marking patterns
• Try a free IGCSE Chemistry quiz

Need help with a 0620 topic? Book a free trial lesson with an IGCSE Chemistry tutor →

Frequently asked questions

What topics were on 0620 Paper 12 May/June 2026? +

All ten syllabus areas. Particles, atoms and bonding and organic chemistry had seven questions each. The rest covered stoichiometry, electrochemistry, energy and rates, acids and salts, the Periodic Table, metals, the environment, and separation and chemical tests.

How many marks is 0620/12 and how long is it? +

It has 40 multiple choice questions, one mark each, for a total of 40 marks. It lasts 45 minutes, so you have just over one minute per question.

What was the answer to the methane combustion question on 0620/12? +

D. 160 g of methane is 10 mol, so it needs 20 mol of oxygen (640 g) and forms 20 mol of water (360 g).

Is 0620/12 the Core or Extended paper? +

Core. Paper 1 is the Core multiple choice paper, sat alongside Paper 3 (Core Theory) and either Paper 5 or Paper 6. Extended candidates sit Paper 2 instead.

Which flame colour was the answer to the last question on 0620/12? +

Blue-green (A). A light blue precipitate with aqueous ammonia that dissolves in excess points to copper(II) ions, and copper(II) gives a blue-green flame.

Where can I download 0620/12 May/June 2026 and its mark scheme? +

Both are free to download and print on the Tutopiya Learning Portal, on the Cambridge IGCSE Chemistry 0620 past papers page.

Ready to Excel in Your Studies?

Get personalised help from Tutopiya's expert tutors. Whether it's IGCSE, IB, A-Levels, or any other curriculum — we match you with the perfect tutor and your first session is free.

Book Your Free Trial