IGCSE Chemistry 0620 Paper 13, Oct/Nov 2025

Substances exist as solids, liquids or gases. In which states of matter are the particles a similar distance apart? A solid, liquid and gas B solid and liquid only C solid and gas only D liquid and gas only

A container with a fixed shape is filled with gas and then sealed. The container is then heated. Which changes take place? 1 The volume of gas decreases. 2 The gas molecules move faster. 3 The pressure inside the cylinder increases. A 1 and 2 B 1 only C 2 and 3 D 3 only

A crystal of sodium chloride is dropped into a beaker of water. Over time, the sodium chloride particles become evenly distributed throughout the water. Which processes occur in this experiment? A both dissolving and diffusion B dissolving only C diffusion only D neither dissolving nor diffusion

The electronic structures of two atoms, P and Q, are shown. P and Q combine together to form a compound. What is the type of bonding in the compound, and what is the formula of the compound?

The electronic configuration of an ion is 2,8,8. What could this ion be?

The table shows the nucleon number and the number of neutrons in one atom of isotopes W, X, Y and Z.

Which statement about W, X, Y and Z is correct? A W and X are isotopes of the same element. B X and Y are isotopes of elements in the same group of the Periodic Table. C Y and Z are isotopes of elements in the same period of the Periodic Table. D Z has a higher proton number than Y.

Which statement about an ionic bond is correct? A It is a strong electrostatic attraction between cations and anions. B It is a strong electrostatic attraction between protons and electrons. C It is a weak electrostatic attraction between cations and anions. D It is a weak electrostatic attraction between protons and electrons.

Which row describes simple molecular compounds?

Boron nitride is a compound of the elements boron and nitrogen. It has a similar structure to diamond. What is likely to be a property of boron nitride? A It conducts electricity. B It is soluble in water. C It is used as a lubricant. D It is very hard.

Which statement defines the term molecular formula? A a formula that shows the total number of atoms in a molecule B a formula that shows the total number of elements in a molecule C a formula that shows the arrangement of different atoms in a molecule D a formula that shows the number and type of different atoms in a molecule

What is the relative formula mass, $M_{\text{r}}$, of calcium hydroxide, ${\text{Ca(OH)}}_2$? A 38 B 58 C 74 D 114

Which statements explain why metal objects are electroplated? 1 Electroplating improves the appearance of the object. 2 Electroplating insulates the metal object. 3 Electroplating makes the metal object more resistant to corrosion. 4 Electroplating makes the metal object softer. A 1 and 2 B 1 and 3 C 2 and 4 D 3 and 4

Three statements about a hydrogen–oxygen fuel cell are listed. 1 The overall equation for the reaction is $2{\text{H}}_2+{\text{O}}_2\to 2{\text{H}}_2\text{O}$. 2 The hydrogen required comes from the air. 3 The waste gas causes respiratory problems. Which statements are correct? A 1, 2 and 3 B 1 only C 2 and 3 only D 3 only

Which reaction pathway diagram represents an endothermic reaction?

Some physical and chemical changes are listed. 1 rusting of iron 2 condensing of steam 3 dissolving of sugar in water 4 cracking of alkanes Which changes are physical changes? A 1 and 3 B 1 and 4 C 2 and 3 D 2 and 4

Blue copper(II) sulfate crystals are heated in air until they turn into a white powder. The powder is allowed to cool and after a few days it starts to turn blue. Why does the white powder start to turn blue? A Carbon dioxide in the air reacts with the powder to form copper(II) carbonate. B The powder reacts with water in the air to form copper(II) hydroxide. C The white copper compound is slowly oxidised. D Water is absorbed from the air and causes the reaction to reverse.

Carbon reacts with silver oxide to form carbon dioxide and silver. Which substance is reduced? A carbon B carbon dioxide C silver D silver oxide

Base Q dissolves in water to make aqueous Q. Aqueous Q is tested with thymolphthalein. Which row gives the colour of thymolphthalein in aqueous Q and the ion responsible for this colour?

Solid calcium hydroxide is added to aqueous ammonium chloride and the mixture is warmed. A gas is produced. What is the name of the gas? A hydrogen B chlorine C carbon dioxide D ammonia

Elements L and M are in the same group of the Periodic Table. Why do L and M have similar chemical properties? A They have the same number of electrons in the nucleus. B They have the same number of electrons in the outer shell. C They have the same number of neutrons in the nucleus. D They have the same number of neutrons in the outer shell.

The diagram shows elements W, X, Y and Z in a section of the Periodic Table. Which statement about the reactivity of the elements is correct? A X is more reactive than Y, and W is more reactive than Z. B X is more reactive than Y, and Z is more reactive than W. C Y is more reactive than X, and W is more reactive than Z. D Y is more reactive than X, and Z is more reactive than W.

Which three compounds are all insoluble in water? A ammonium carbonate, silver chloride and sodium sulfate B barium sulfate, calcium chloride and magnesium hydroxide C calcium nitrate, magnesium carbonate and lead(II) hydroxide D calcium sulfate, magnesium hydroxide and silver chloride

18 carat gold contains 75% gold and 25% copper by mass. Which statements about 18 carat gold are correct? 1 It is a mixture. 2 It is a compound. 3 It is an alloy. 4 It conducts electricity. A 1, 2 and 4 B 1, 3 and 4 C 1 and 3 only D 2 and 3

The properties of four metals, E, F, G and H, are shown. E does not react with cold water, but reacts with steam. F does not react with water or dilute acid, but the oxide of F is reduced by carbon. The oxide of G is not reduced by carbon, but G reacts vigorously with cold water. H does not react with water or steam, but reacts with dilute acid. What is the order of reactivity of the metals starting with the most reactive?

Four substances, or groups of substances, found in water from a natural source are listed. 1 some metal compounds 2 plastics 3 dissolved oxygen 4 nitrates and phosphates from fertilisers and detergents Which substances found in water from a natural source can be beneficial to aquatic life? A 1 and 3 B 1 and 4 C 2 and 3 D 2 and 4

Which element is used to remove tastes and odours in the treatment of the domestic water supply? A chlorine B carbon C calcium D copper

NPK fertilisers are mixtures of salts used to improve plant growth. Which salt could be used as a component of an NPK fertiliser? A sodium nitrate B aluminium sulfate C magnesium chloride D calcium ethanoate

Plants produce glucose by photosynthesis. What is essential for this process? 1 carbon dioxide 2 oxygen 3 light 4 water A 1 and 2 B 1, 3 and 4 C 1 and 3 only D 2, 3 and 4

Two reactions, M and N, both form carbon dioxide. $${\text{CaCO}}_3\stackrel{\text{M}}{\to }{\text{CO}}_2\stackrel{\text{N}}{\leftarrow }{\text{CH}}_4$$ Which types of reaction are M and N?

The molecular formulae of four compounds are shown. $${\text{C}}_2{\text{H}}_2{\text{C}}_3{\text{H}}_8{\text{C}}_4{\text{H}}_8{\text{C}}_5{\text{H}}_{10}$$ How many of these compounds are in the alkane homologous series? A 1 B 2 C 3 D 4

Which type of reaction takes place when pentane reacts with chlorine? A polymerisation B addition C substitution D cracking

Which bar chart shows the percentage composition of natural gas?

Which statement about alcohols is correct? A Alcohols have the same functional group as carboxylic acids. B Ethanol is an alcohol that is formed by fermentation at 300 °C. C Ethanol is the alcohol produced in the addition reaction between ethene and hydrogen. D Water is produced from the combustion of alcohols.

The equation shows the reaction between ethanoic acid and solid P to produce Q and hydrogen. $$\text{ethanoic acid}+\text{P}\to \text{Q}+\text{hydrogen}$$ Which row identifies P and Q?

The diagram shows one repeat unit of a polymer. Which row gives the name of the polymer and of the monomer used to make it?

Some properties of a plastic pollutant are listed. 1 It is a poor conductor of electricity. 2 It does not react with water. 3 It is resistant to oxidation. 4 It has low density. Which properties explain why this plastic is difficult to remove from the environment? A 1 and 3 B 1 and 4 C 2 and 3 D 2 and 4

The graph shows the volume of hydrogen produced over time in a chemical reaction. A student uses a stop-watch. Which other item of apparatus is used to take measurements to produce this graph? A beaker B gas syringe C pipette D test-tube

A student uses paper chromatography to identify the food dyes in a coloured sweet, S. The student uses four known food dyes, W, X, Y, and Z, and ethanol as the solvent. The chromatogram obtained is shown. Which statements are correct? 1 S contains only two dyes. 2 X is insoluble in ethanol. 3 S contains Y and Z. 4 S contains W. A 1, 2 and 4 B 2 and 3 C 2 and 4 only D 4 only

An aqueous cation reacts with aqueous sodium hydroxide to form a white precipitate. The precipitate is insoluble in excess sodium hydroxide. What is the aqueous cation? A aluminium ion B calcium ion C chromium ion D zinc ion

A piece of damp red litmus paper is put into a test-tube of gas. The litmus paper turns white. Which gas is in the test-tube? A ammonia B carbon dioxide C chlorine D oxygen