Chemistry 0620 · Cambridge O Level / IGCSE
Paper 3: Theory (Core)
1 hour 15 minutes · 80 marks · 50%
- Duration
- 1 hour 15 minutes
- Marks
- 80
- Tier
- Core
- Practice here
- 75
What is on this paper
- Short-answer and structured questions
- Externally assessed
How it is weighted
- 50%
Which papers you sit
All candidates take three components.
Core candidates take Paper 1, Paper 3 and either Paper 5 or Paper 6, and are eligible for grades C to G.
Extended candidates take Paper 2, Paper 4 and either Paper 5 or Paper 6, and are eligible for grades A* to G.
Assessment details are taken from the official Cambridge Chemistry 0620 syllabus for 2026-2028. Read the syllabus ↗
Practise the topics on Paper 3
All Chemistry topics →75 original questions, each with a full worked solution. Free to read, no account needed.
The Mole and Stoichiometry
Write chemical formulae and balanced equations; use relative atomic and molecular mass; convert between mass, moles…
Atomic Structure and Isotopes
Describe protons, neutrons and electrons and their relative charges and masses; use proton and nucleon numbers to work…
Chemical Bonding (Ionic, Covalent and Metallic)
Explain how ions and ionic lattices form, draw dot-and-cross diagrams for simple covalent molecules, and link bonding…
Rates of Reaction
Describe and investigate how concentration, pressure, surface area, temperature and catalysts change reaction rate…
Acids, Bases and Salts
Describe reactions of acids with metals, bases and carbonates; use indicators and the pH scale; classify oxides…
Electrolysis
Predict and explain the products of electrolysing molten compounds and aqueous solutions; write electrode…
The Periodic Table and Group Trends
Relate position in the Periodic Table to electronic configuration and metallic character; describe and predict trends…
Hydrocarbons: Alkanes and Alkenes
Use general formulae, displayed formulae and homologous-series ideas; name simple organic compounds; describe…
Reactivity Series and Metal Extraction
Place metals in order of reactivity from their reactions with water, steam and acids; use displacement reactions as…
Exothermic and Endothermic Reactions
Classify reactions as exothermic or endothermic from temperature changes; interpret and draw reaction pathway diagrams…
States of Matter and Diffusion
Describe solids, liquids and gases and changes of state using the kinetic particle model; interpret heating and…
Redox Reactions
Identify oxidation and reduction in terms of oxygen gain/loss; use oxidation numbers and electron transfer…
Chemical Tests for Ions and Gases
Identify cations using aqueous sodium hydroxide and aqueous ammonia, anions with the standard reagent tests, and…
Chemistry of the Environment
Describe water treatment and tests for water; NPK fertilisers; the composition of clean air, sources and effects of…
Reversible Reactions and Equilibrium
Recognise reversible reactions and the ⇌ symbol, including hydrated salts; describe dynamic equilibrium and predict…