IGCSE Chemistry 0620/12 Past Paper, Oct/Nov 2025

0620/12 · Oct/Nov 2025

Water exists as solid ice, liquid water and steam. In which states can water easily be compressed to half its original volume? A ice, liquid water and steam B liquid water and steam only C liquid water only D steam only

The melting point of sulfur is 113 °C. Which row describes the arrangement and movement of sulfur particles at 25 °C?

	arrangement of particles	movement of particles
$A$	regular	vibrate about fixed positions
$B$	regular	random
$C$	random	vibrate about fixed positions
$D$	random	random

Solid Y is added to an excess of hot water. A blue solution forms and a brown solid remains. The brown solid is filtered off and dried. The brown solid conducts electricity. What is Y? A a compound that contains a metal B a mixture that contains a metal C a pure substance that is a metal D a pure substance that is a non-metal

Which statement about the structure of an atom is correct? A Electrons and protons each have a relative mass of 1, and neutrons have no charge. B Electrons have a relative mass of 1 and a negative charge. C Protons have a relative mass of 1 and a negative charge. D Neutrons have a relative mass of 1 and no charge.

The diagram shows the electronic configuration of a particle with a nucleon number of 40. The table shows the suggestions that three students, 1, 2 and 3, made to identify the particle.

	student
	$1$	$2$	$3$
particle	Ar	Cl	${Ca}^{2 +}$

Which students are correct? A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

What is defined as different atoms of the same element with the same number of protons but different numbers of neutrons? A homologous series B isotopes C mass number D the group number

The electronic configurations of atoms Q and R are shown. Q and R form an ionic compound. What is the formula of the compound? A $R_{7} Q$ B $R_{4} Q_{2}$ C $RQ$ D ${RQ}_{7}$

Which properties are typical of simple molecules? 1 high melting point 2 good electrical conductivity 3 low boiling point 4 high malleability A 1 and 2 B 2 and 4 C 3 and 4 D 3 only

Diamond is extremely hard and does not conduct electricity. Which statement explains these properties? A It has positive carbon ions surrounded by delocalised electrons. B It has strong ionic bonds between each carbon atom. C It has delocalised electrons, and each carbon atom forms three covalent bonds with other carbon atoms. D It has no delocalised electrons, and each carbon atom forms four covalent bonds with other carbon atoms.

Which equation represents the complete combustion of butane, $C_{4} H_{10}$ ? A $2 C_{4} H_{10} + 5 O_{2} \to 8 C + 10 H_{2} O$ B $2 C_{4} H_{10} + 9 O_{2} \to 8 CO + 10 H_{2} O$ C $2 C_{4} H_{10} + 13 O_{2} \to 8 {CO}_{2} + 10 H_{2} O$ D $C_{4} H_{10} + 4 O_{2} \to 4 {CO}_{2} + 5 H_{2}$

What is the relative formula mass of calcium sulfate, ${CaSO}_{4}$ ? A 88 B 92 C 136 D 232

What is the product at each electrode when molten silver iodide is electrolysed using inert electrodes?

	cathode	anode
$A$	hydrogen	iodine
$B$	iodine	silver
$C$	silver	iodine
$D$	silver	oxygen

Which row describes a product at each electrode when dilute sulfuric acid is electrolysed using inert electrodes?

	product at anode	product at cathode
$A$	$10 {cm}^{3} of a colourless gas$	$10 {cm}^{3} of a brown gas$
$B$	$10 {cm}^{3} of a colourless gas$	$20 {cm}^{3} of a colourless gas$
$C$	$20 {cm}^{3} of a colourless gas$	$10 {cm}^{3} of a colourless gas$
$D$	$20 {cm}^{3} of a brown gas$	$10 {cm}^{3} of a colourless gas$

Which experiment is the most exothermic?

	$initial temperature /^{\circ} C$	$final temperature /^{\circ} C$
$A$	$20$	$5$
$B$	$20$	$32$
$C$	$25$	$12$
$D$	$25$	$34$

In which test-tube is a physical change taking place? A water and sodium chloride B water and iron nail C dilute hydrochloric acid and zinc D dilute hydrochloric acid and calcium carbonate

Which items of apparatus are essential when measuring the effect of temperature on the rate of any reaction? 1 balance 2 gas syringe 3 stop-watch 4 thermometer A 1 and 2 B 1 and 3 C 2 and 4 D 3 and 4

When pink cobalt(II) chloride is heated, it forms a blue solid and water. When water is added to the blue solid, it releases heat and a pink solid is formed. Which row describes the type of reaction that occurs and the pink cobalt(II) chloride?

	type of reaction	pink cobalt(II) chloride
$A$	non-reversible	anhydrous
$B$	non-reversible	hydrated
$C$	reversible	anhydrous
$D$	reversible	hydrated

What is the oxidation number of iron in iron(III) oxide, ${Fe}_{2} O_{3}$ ? A +2 B +3 C –2 D –3

Which substances react with dilute hydrochloric acid to form aqueous copper(II) chloride? 1 copper 2 copper(II) oxide 3 copper(II) carbonate 4 copper(II) hydroxide A 1, 2, 3 and 4 B 1, 2 and 3 only C 2, 3 and 4 only D 2 and 3 only

A few drops of thymolphthalein and methyl orange are added separately to two test-tubes containing solution X. Solution Y is then added to both test-tubes until present in excess. The colours of the indicators before and after addition of solution Y are shown.

	colour of thymolphthalein	colour of methyl orange
solution X only	colourless	red
mixture of solution X and excess solution Y	blue	yellow

What is solution Y? A $HCl(aq)$ B $NaOH(aq)$ C $H_{2} O(l)$ D $NaCl(aq)$

Which mixture of solids is separated by adding water, stirring, and then using filtration? A ammonium chloride and silver chloride B barium sulfate and calcium sulfate C copper(II) hydroxide and iron(III) hydroxide D potassium nitrate and sodium nitrate

The character of the elements and charges on the ions of the elements change across the Periodic Table. Which row describes the elements on the left and the elements on the right of the Periodic Table?

	elements on the left		elements on the right
	character	charge on ion	character	charge on ion
$A$	metallic	positive	non-metallic	negative
$B$	metallic	negative	non-metallic	positive
$C$	non-metallic	positive	metallic	negative
$D$	non-metallic	negative	metallic	positive

Which statement describes a general trend down Group I? A The melting point increases. B The reactivity decreases. C The density increases. D The total number of electrons decreases.

Which statement describes the appearance of the named halogen at room temperature and pressure? A Chlorine is a colourless gas. B Chlorine is a red-brown liquid. C Iodine is a purple gas. D Iodine is a grey-black solid.

Osmium is a transition element. Which row gives the expected properties of osmium?

	melting point	density at r.t.p.	compounds formed
$A$	high	high	coloured
$B$	high	high	white
$C$	high	low	white
$D$	low	high	coloured

Which statement about the element neon, Ne, is correct? A It is in Group VII of the Periodic Table. B It reacts rapidly with oxygen. C It exists as diatomic molecules. D Its atoms have a full outer shell of electrons.

Substance G reacts with: ● dilute acids to produce hydrogen ● steam to produce a basic oxide ● oxygen to produce a basic oxide. What is substance G? A magnesium B phosphorus C silicon D silver

Which row describes two properties and a use of the named metal?

	metal	property 1	property 2	use
$A$	aluminium	high density	resistant to corrosion	food containers
$B$	aluminium	low density	good electrical conductivity	overhead power cables
$C$	copper	good electrical conductivity	low ductility	electrical wiring
$D$	copper	high melting point	low density	aircraft manufacture

Four methods to prevent the rusting of iron are listed. 1 alloying 2 coating with plastic 3 greasing 4 painting Which methods are barrier methods? A 1, 2 and 3 B 1 and 4 C 2, 3 and 4 D 3 and 4 only

Iron is extracted from hematite in a blast furnace. Which reaction involves thermal decomposition? A Calcium carbonate reacts to form calcium oxide and carbon dioxide. B Carbon (coke) reacts with oxygen to form carbon dioxide. C Carbon dioxide reacts with carbon to form carbon monoxide. D Iron(III) oxide reacts with carbon monoxide to form iron and carbon dioxide.

Clean, dry air contains nitrogen, oxygen and small amounts of other gases. The noble gases have been left out of the table. Which row shows the composition of clean, dry air?

	$nitrogen / %$	$oxygen / %$	other gases
$A$	$21$	$78$	small amount of carbon dioxide
$B$	$21$	$78$	small amount of carbon monoxide
$C$	$78$	$21$	small amount of carbon dioxide
$D$	$78$	$21$	small amount of carbon monoxide

Some substances found in water from natural sources are potentially harmful. Which substance contains microbes that cause disease? A metal compounds B nitrates C phosphates D sewage

Gas X is a waste gas from digestion in animals. Gas Y is formed when gas X is burned with an insufficient amount of oxygen. Gas Z is formed when gas X is burned with an excess of oxygen. What are X, Y and Z?

	X	Y	Z
$A$	carbon dioxide	methane	carbon monoxide
$B$	carbon monoxide	methane	carbon dioxide
$C$	methane	carbon dioxide	carbon monoxide
$D$	methane	carbon monoxide	carbon dioxide

Which statement about photosynthesis is correct? A It decreases the amount of oxygen in the atmosphere. B It is a reaction between carbon dioxide and water. C It produces a gas that contributes to increased global warming. D It requires a temperature greater than 50 °C.

L and M are different homologous series. The first three members of homologous series L all decolourise aqueous bromine. The first three members of homologous series M all dissolve in water to give solutions with a pH below 7. What are the general formulae for homologous series L and M?

	homologous series L	homologous series M
$A$	$C_{n} H_{2 n}$	$C_{n} H_{2 n + 1} COOH$
$B$	$C_{n} H_{2 n}$	$C_{n} H_{2 n + 1} OH$
$C$	$C_{n} H_{2 n + 2}$	$C_{n} H_{2 n + 1} OH$
$D$	$C_{n} H_{2 n + 2}$	$C_{n} H_{2 n + 1} COOH$

Which structure represents an unsaturated hydrocarbon? A ethane ( ${CH}_{3} {CH}_{3}$ ) B ethanoic acid ( ${CH}_{3} COOH$ ) C methane ( ${CH}_{4}$ ) D ethene ( ${CH}_{2} = {CH}_{2}$ )

Petroleum is a mixture of compounds. Which elements are present in all of these compounds? 1 carbon 2 hydrogen 3 oxygen A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Which statement about ethanol explains why it is used as a fuel? A It is a colourless liquid. B It has a low density. C It forms carbon dioxide when burned. D It releases energy when burned.

The table shows the observations of two tests on an aqueous solution of a solid.

test	observations
add acidified silver nitrate	white precipitate
add aqueous sodium hydroxide	green precipitate that dissolves in excess sodium hydroxide

What is the solid? A chromium(III) bromide B chromium(III) chloride C iron(II) bromide D iron(II) chloride

W is a mixture of coloured dyes. It is thought to contain dyes P, Q, R or S. A sample of W is separated by chromatography. The chromatogram is shown. What does the chromatogram show? A W contains P and S only. B W contains P and R only. C W contains P, Q and S. D W contains P, R and S.

IGCSE Chemistry 0620 Paper 12, Oct/Nov 2025

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