Chemistry 0620/12 October/November 2025: question paper and mark scheme

Question

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

Question

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

Question

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

Question

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.

Question

The diagram shows the electronic configuration of a particle with a nucleon number of 40. 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 Ca2+ Which students are correct? A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Question

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

Question

The electronic configurations of atoms Q and R are shown. Q R Q and R form an ionic compound. What is the formula of the compound? A R7Q B R4Q2 C RQ D RQ7

Question

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

Question

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.

Question

Which equation represents the complete combustion of butane, C4H10? A 2C4H10 + 5O2 → 8C + 10H2O B 2C4H10 + 9O2 → 8CO + 10H2O C 2C4H10 + 13O2 → 8CO2 + 10H2O D C4H10 + 4O2 → 4CO2 + 5H2

Question

What is the relative formula mass of calcium sulfate, CaSO4? A 88 B 92 C 136 D 232

Question

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

Question

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 cm3 of a colourless gas 10 cm3 of a brown gas B 10 cm3 of a colourless gas 20 cm3 of a colourless gas C 20 cm3 of a colourless gas 10 cm3 of a colourless gas D 20 cm3 of a brown gas 10 cm3 of a colourless gas

Question

Which experiment is the most exothermic? initial final temperature / °C temperature / °C A 20 5 B 20 32 C 25 12 D 25 34

Question

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

Question

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

Question

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

Question

What is the oxidation number of iron in iron(III) oxide, Fe2O3? A +2 B +3 C –2 D –3

Question

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

Question

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 colour of thymolphthalein methyl orange solution X only colourless red mixture of solution X and blue yellow excess solution Y What is solution Y? A HCl (aq) B NaOH(aq) C H2O(l) D NaCl (aq)

Question

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

Question

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

Question

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.

Question

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.

Question

Osmium is a transition element. Which row gives the expected properties of osmium? density compounds melting point at r.t.p. formed A high high coloured B high high white C high low white D low high coloured

Question

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.

Question

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

Question

Which row describes two properties and a use of the named metal? metal property 1 property 2 use A aluminium high density resistant food to corrosion containers B aluminium low density good electrical overhead conductivity power cables C copper good electrical low ductility electrical wiring conductivity D copper high low density aircraft melting point manufacture

Question

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

Question

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.

Question

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

Question

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

Question

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

Question

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.

Question

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 homologous series L series M A CnH2n CnH2n+1COOH B CnH2n CnH2n+1OH C CnH2n+2 CnH2n+1OH D CnH2n+2 CnH2n+1COOH

Question

Which structure represents an unsaturated hydrocarbon? A B C D H H H O H H H H C C H H C C H C H C C H H H O H H H H

Question

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

Question

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.

Question

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

Question

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. solvent front baseline W P Q R S 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. The Periodic Table of Elements Group I II III IV V VI VII VIII 1 2 H He hydrogen helium Key 1 4 3 4 atomic number 5 6 7 8 9 10 Li Be atomic symbol B C N O F Ne lithium beryllium name boron carbon nitrogen oxygen fluorine neon 7 9 relative atomic mass 11 12 14 16 19 20 11 12 13 14 15 16 17 18 Na Mg Al Si P S Cl Ar sodium magnesium aluminium silicon phosphorus sulfur chlorine argon 23 24 27 28 31 32 35.5 40 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr potassium calcium scandium titanium vanadium chromium manganese iron cobalt nickel copper zinc gallium germanium arsenic selenium bromine krypton 39 40 45 48 51 52 55 56 59 59 64 65 70 73 75 79 80 84 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe rubidium strontium yttrium zirconium niobium molybdenum technetium ruthenium rhodium palladium silver cadmium indium tin antimony tellurium iodine xenon 16 85 88 89 91 93 96 – 101 103 106 108 112 115 119 122 128 127 131 55 56 57–71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 lanthanoids Cs Ba Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn caesium barium hafnium tantalum tungsten rhenium osmium iridium platinum gold mercury thallium lead bismuth polonium astatine radon 133 137 178 181 184 186 190 192 195 197 201 204 207 209 – – – 87 88 89–103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 actinoids Fr Ra Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og francium radium rutherfordium dubnium seaborgium bohrium hassium meitnerium darmstadtium roentgenium copernicium nihonium flerovium moscovium livermorium tennessine oganesson – – – – – – – – – – – – – – – – – 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 lanthanoids La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu lanthanum cerium praseodymium neodymium promethium samarium europium gadolinium terbium dysprosium holmium erbium thulium ytterbium lutetium 139 140 141 144 – 150 152 157 159 163 165 167 169 173 175 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 actinoids Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr actinium thorium protactinium uranium neptunium plutonium americium curium berkelium californium einsteinium fermium mendelevium nobelium lawrencium – 232 231 238 – – – – – – – – – – – The volume of one mole of any gas is 24 dm3 at room temperature and pressure (r.t.p.).