Cambridge IGCSE Chemistry (9-1) 0971 — 2025 May/June Paper 2 · Variant 1

This document has 16 pages. IB25 06_0971_21/FP © UCLES 2025 [Turn over *7180507963* Cambridge IGCSE™(9–1) CHEMISTRY 0971/21 Paper 2 Multiple Choice (Extended) May/June 2025 45 minutes You must answer on the multiple choice answer sheet. You will need: Multiple choice answer sheet Soft clean eraser Soft pencil (type B or HB is recommended) INSTRUCTIONS  There are forty questions on this paper. Answer all questions.  For each question there are four possible answers A, B, C and D. Choose the one you consider correct and record your choice in soft pencil on the multiple choice answer sheet.  Follow the instructions on the multiple choice answer sheet.  Write in soft pencil.  Write your name, centre number and candidate number on the multiple choice answer sheet in the spaces provided unless this has been done for you.  Do not use correction fluid.  Do not write on any bar codes.  You may use a calculator. INFORMATION  The total mark for this paper is 40.  Each correct answer will score one mark.  Any rough working should be done on this question paper.  The Periodic Table is printed in the question paper.

2 © UCLES 2025 0971/21/M/J/25 1 A gas is placed in a sealed container with a fixed volume. The gas is heated. Which statements are correct? 1 The gas molecules move around faster. 2 The gas particles collide with the walls of the container more frequently. 3 The pressure in the container decreases. A 1 and 2 B 1 only C 2 and 3 D 2 only 2 A sample of ethanol is heated at a constant rate. The heating curve for this sample is shown. temperature time 1 2 3 4 5 6 Which statement about the heating curve is correct? A Ethanol changes its physical state between 3 and 4. B Ethanol condenses between 2 and 3. C Energy is absorbed between 3 and 4 but not absorbed between 4 and 5. D More energy is absorbed between 4 and 5 than between 2 and 3. 3 Which atom has an equal number of protons, neutrons and electrons? A 40Ar B 1H C 23Na D 14N 4 The only naturally occurring isotopes in a sample of europium are 151Eu and 153Eu. This sample of europium has a relative atomic mass, Ar, of 152. What is the percentage of 151Eu present in this sample to three significant figures? A 0.987% B 50.0% C 76.0% D 98.7%

3 © UCLES 2025 0971/21/M/J/25 [Turn over 5 Which statement about potassium chloride is correct? A It has a high melting point because it is a giant structure with strong covalent bonds. B It conducts electricity when solid because of its oppositely charged ions. C It conducts electricity when molten because its ions can move. D It is insoluble in water because of its strong bonding. 6 Which dot-and-cross diagram shows the outer shell electron arrangement in a molecule of nitrogen? N N A N N B N N C N N D 7 Which statement about silicon(IV) oxide is correct? A It contains silicon ions and oxide ions arranged in a giant lattice. B It is used in electrical circuits because it can conduct electricity. C Its bonds each contain one shared pair of electrons. D Its atoms are arranged in the same way as the atoms in graphite.

4 © UCLES 2025 0971/21/M/J/25 8 Three organic molecules are described. ● The molecular formula of propanoic acid is CH3CH2COOH. ● The molecular formula of lactic acid is CH3CH(OH)COOH. ● A glucose molecule consists of 6 carbon atoms, 6 oxygen atoms and 12 hydrogen atoms only. Which molecules have the same empirical formula? A propanoic acid, lactic acid and glucose B propanoic acid and lactic acid only C propanoic acid and glucose only D lactic acid and glucose only 9 Calcium carbonate reacts with dilute hydrochloric acid. The equation for the reaction is shown. CaCO3 + 2HCl  CaCl 2 + H2O + CO2 1.00 g of calcium carbonate is added to 50.0 cm3 of 0.0500 mol / dm3 hydrochloric acid. Which volume of carbon dioxide is made in this reaction? A 30 cm3 B 60 cm3 C 120 cm3 D 240 cm3 10 The diagram shows the electroplating of a steel object. steel object copper electrode aqueous copper(II) sulfate + – power supply A student makes three statements. 1 The steel object turns a reddish-brown colour. 2 The aqueous copper(II) sulfate changes to a paler blue colour. 3 The copper electrode becomes thinner. Which statements are correct? A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

5 © UCLES 2025 0971/21/M/J/25 [Turn over 11 Concentrated aqueous sodium chloride is electrolysed using inert electrodes. Which equation shows the correct ionic half-equation for the reaction at the anode? A Cl – + e–  Cl B 2Cl –  Cl 2 + 2e– C H+  H + e– D 2H+ + 2e–  H2 12 Which equation represents the overall reaction in a hydrogen–oxygen fuel cell? A 2H2 + O2  2H2O B 2H2O  2H2 + O2 C H2 + O2  H2O2 D H2O2  H2 + O2

6 © UCLES 2025 0971/21/M/J/25 13 Water is added to anhydrous copper(II) sulfate in a test-tube. The mixture becomes hot. Which type of reaction and reaction pathway diagram apply to this reaction? type of reaction reaction pathway diagram A endothermic energy progress of reaction reactants products B endothermic reactants products energy progress of reaction C exothermic energy progress of reaction reactants products D exothermic reactants products energy progress of reaction 14 The equation represents the reaction between ethanoic acid and ethanol. CH3COOH + CH3CH2OH CH3COOCH2CH3 + H2O Which type of reaction does this show? A addition B neutralisation C reduction D reversible

7 © UCLES 2025 0971/21/M/J/25 [Turn over 15 The graph shows the results of adding excess calcium carbonate to hydrochloric acid at 50 °C and at 30 °C. Only the temperature is changed. total volume of carbon dioxide given off / cm3 time / s 0 0 50 °C 30 °C Which row describes the reacting particles at 30 °C compared to those at 50 °C? frequency of collisions between particles average kinetic energy of particles A higher higher B higher lower C lower higher D lower lower 16 Industrially, ammonia is made by the Haber process. The equation is shown. N2(g) + 3H2(g) 2NH3(g) H = –92 kJ / mol The conditions used are 450 °C and 200 atm. Which statements about the conditions are correct? 1 Temperatures below 450 °C give a lower rate of reaction. 2 Temperatures below 450 °C give a lower yield of ammonia. 3 Pressures above 200 atm give a lower yield of ammonia. 4 Pressures above 200 atm are too expensive to maintain. A 1 and 2 B 1 and 4 C 2 and 3 D 3 and 4

8 © UCLES 2025 0971/21/M/J/25 17 Ethanol is warmed with acidified aqueous potassium manganate(VII). Which row describes the type of reaction of the ethanol and the colour change observed in the reaction mixture? type of reaction colour change A oxidation colourless to purple B oxidation purple to colourless C reduction colourless to purple D reduction purple to colourless 18 Two experiments involving acids R or S are done. ● 0.10 mol of acid R completely dissolves in 500 cm3 of water. 0.0048 mol of acid R is dissociated in the solution. ● 0.10 mol of acid S completely dissolves in 500 cm3 of water. 0.0179 mol of acid S is dissociated in the solution. Which statement about acids R and S is correct? A Acid R is a strong acid, and acid S is a weak acid. B Acid R is a weak acid, and acid S is a strong acid. C Acid R and acid S are both strong acids. D Acid R and acid S are both weak acids. 19 Lead(II) sulfate is an insoluble salt. Which process is not used to prepare a pure sample of this salt? A crystallisation B drying C filtration D precipitation

9 © UCLES 2025 0971/21/M/J/25 [Turn over 20 The formulae of two hydrated salts are shown. ● CuSO4•xH2O ● CoCl 2•yH2O What are the values of x and y? x y A 5 5 B 5 6 C 6 5 D 6 6 21 The properties of the elements change from left to right across the Periodic Table. Which statement describes how the properties change across Period 3? A Elements change from gases to solids. B Elements change from non-conductors to electrical conductors. C Elements change from metal to non-metal. D Elements have a decreasing number of electron shells. 22 Which property decreases down Group VII of the Periodic Table, from chlorine to iodine? A atomic number B density C reactivity D melting point 23 Some properties of elements are listed. 1 They have good electrical conductivity. 2 They have high melting points. 3 They are malleable. 4 They have ions with variable oxidation numbers. Which properties are correct for both iron and lithium? A 1 and 3 B 1 and 4 C 2 and 3 D 2 and 4

10 © UCLES 2025 0971/21/M/J/25 24 Two statements about noble gases are listed. 1 Noble gases are reactive, monatomic gases. 2 Noble gases all have a full outer shell of electrons. Which statements about noble gases are correct? A Both statements are correct, and statement 2 explains statement 1. B Both statements are correct but statement 2 does not explain statement 1. C Statement 1 is correct but statement 2 is not correct. D Statement 2 is correct but statement 1 is not correct. 25 Which statement about the properties and uses of copper is correct? A It is used in electrical wiring, and it is ductile. B It is mixed with tin to make the alloy brass. C It is used in overhead electrical cables because it has a low density. D It is used in takeaway food containers because of its resistance to corrosion. 26 Three statements about solid Z are listed. ● It reacts with dilute hydrochloric acid to produce hydrogen. ● It reacts very slowly with cold water and quickly with steam. ● It is a good thermal conductor. What is solid Z? A gold B magnesium C potassium D silver

11 © UCLES 2025 0971/21/M/J/25 [Turn over 27 Four metals J, K, L and M are added separately to aqueous solutions of their ions. The results are shown. aqueous ions metal J2+ K2+ L2+ M2+ J     key K      = reaction L      = no reaction M     Which statement about the metals is correct? A J has a greater tendency to form positive ions than K. B L has a greater tendency to form positive ions than J. C K has a greater tendency to form positive ions than L. D M has a greater tendency to form positive ions than K. 28 Which process is used in the extraction of iron from hematite? A electrolysis B precipitation C reduction D fractional distillation 29 Galvanising prevents iron from rusting. Which statements about galvanising are correct? 1 Galvanising involves coating the iron with silver. 2 Galvanising prevents oxygen and water from coming into contact with the iron. 3 Galvanising works because the metal coating loses electrons more readily than iron. A 1, 2 and 3 B 1 and 3 only C 2 and 3 only D 2 only

12 © UCLES 2025 0971/21/M/J/25 30 Nitrogen, phosphorus and potassium are essential elements for improved plant growth. Which mixture provides all three essential elements? mixture formulae A ammonium phosphate + potassium chloride (NH4)3PO4 + KCl B ammonium phosphate + ammonium nitrate (NH4)3PO4 + NH4NO3 C ammonium phosphate + ammonium chloride (NH4)3PO4 + NH4Cl D ammonium nitrate + potassium chloride NH4NO3 + KCl 31 Which statements help explain why an increasing amount of carbon dioxide or methane in the atmosphere causes global warming? 1 Carbon dioxide absorbs thermal energy from the Earth. 2 Methane does not absorb thermal energy from the Sun. 3 Carbon dioxide does not reflect thermal energy from the Sun to the Earth. 4 Methane reflects thermal energy from the Earth back to the Earth. A 1 and 3 B 1 and 4 C 2 and 3 D 2 and 4 32 The exhaust gases from cars contain oxides of nitrogen. How are these oxides of nitrogen formed? A Nitrogen and oxygen from the air react together at the high temperatures in the engine. B Nitrogen and oxygen from the petrol react together in the car exhaust. C Nitrogen from the petrol reacts with oxygen at the high temperatures in the engine. D Nitrogen reacts with oxygen from the air in the catalytic converter.

13 © UCLES 2025 0971/21/M/J/25 [Turn over 33 The structural formula of methyl ethanoate is CH3COOCH3. Which compounds are structural isomers of methyl ethanoate? 1 HCOOCH2CH3 2 CH3CH2COOH 3 HOCH2CH2CH2OH A 1, 2 and 3 B 1 and 2 only C 2 and 3 only D 3 only 34 What is the total number of covalent bonds in one molecule of propane? A 8 B 9 C 10 D 11 35 Industrially, ethanol is produced by fermentation or by the reaction of ethene with steam. Which row is correct? fermentation ethene + steam A uses a temperature of 100 °C uses a temperature of 350 °C B needs the presence of yeast does not need a catalyst C slow reaction fast reaction D high yield of ethanol low yield of ethanol 36 Some properties of an organic compound, J, are listed. ● It is a liquid at room temperature. ● It is soluble in water. ● A solution of J reacts with calcium carbonate to form carbon dioxide. ● A solution of J has a pH of 3. In which homologous series does J belong? A alkane B alkene C alcohol D carboxylic acid

14 © UCLES 2025 0971/21/M/J/25 37 The structures of two monomers that are used to make a condensation polymer are shown. HO C H H C H H C H H OH C C C O O OH HO Which structure represents one repeat unit of the condensation polymer formed? C O C O C H A H C H H C H H C O C O O C H B H C H H C O H H C O O C H D H C H H C O H H C O C O O C H C H C H H C O H H C O 38 Which item of apparatus is used to measure 25.0 cm3 of aqueous sodium hydroxide? A B C D 39 Which method is used to obtain copper(II) sulfate crystals from an aqueous solution of copper(II) sulfate? A chromatography B condensation C evaporation D filtration

15 Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity. To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge Assessment International Education Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cambridgeinternational.org after the live examination series. Cambridge Assessment International Education is part of Cambridge Assessment. Cambridge Assessment is the brand name of the University of Cambridge Local Examinations Syndicate (UCLES), which is a department of the University of Cambridge. © UCLES 2025 0971/21/M/J/25 40 A mixture of four different colourless amino acids is analysed by paper chromatography. The final chromatogram is shown. solvent front baseline Why does the chromatogram only show three spots? A A locating agent is not used. B One of the amino acids is insoluble in the solvent. C The solvent front is too near the top of the paper. D Two of the amino acids have the same Rf value.

16 © UCLES 2025 0971/21/M/J/25 Group The Periodic Table of Elements 1 H hydrogen 1 2 He helium 4 I II III IV V VI VII VIII 3 Li lithium 7 4 Be beryllium 9 atomic number atomic symbol Key name relative atomic mass 11 Na sodium 23 12 Mg magnesium 24 19 K potassium 39 20 Ca calcium 40 37 Rb rubidium 85 38 Sr strontium 88 55 Cs caesium 133 56 Ba barium 137 87 Fr francium – 88 Ra radium – 5 B boron 11 13 Al aluminium 27 31 Ga gallium 70 49 In indium 115 81 Tl thallium 204 113 Nh nihonium – 6 C carbon 12 14 Si silicon 28 32 Ge germanium 73 50 Sn tin 119 82 Pb lead 207 22 Ti titanium 48 40 Zr zirconium 91 72 Hf hafnium 178 104 Rf rutherfordium – 23 V vanadium 51 41 Nb niobium 93 73 Ta tantalum 181 105 Db dubnium – 24 Cr chromium 52 42 Mo molybdenum 96 74 W tungsten 184 106 Sg seaborgium – 25 Mn manganese 55 43 Tc technetium – 75 Re rhenium 186 107 Bh bohrium – 26 Fe iron 56 44 Ru ruthenium 101 76 Os osmium 190 108 Hs hassium – 27 Co cobalt 59 45 Rh rhodium 103 77 Ir iridium 192 109 Mt meitnerium – 28 Ni nickel 59 46 Pd palladium 106 78 Pt platinum 195 110 Ds darmstadtium – 29 Cu copper 64 47 Ag silver 108 79 Au gold 197 111 Rg roentgenium – 30 Zn zinc 65 48 Cd cadmium 112 80 Hg mercury 201 112 Cn copernicium – 114 Fl flerovium – 116 Lv livermorium – 7 N nitrogen 14 15 P phosphorus 31 33 As arsenic 75 51 Sb antimony 122 83 Bi bismuth 209 115 Mc moscovium – 8 O oxygen 16 16 S sulfur 32 34 Se selenium 79 52 Te tellurium 128 84 Po polonium – 9 F fluorine 19 17 Cl chlorine 35.5 35 Br bromine 80 53 I iodine 127 85 At astatine – 117 Ts tennessine – 10 Ne neon 20 18 Ar argon 40 36 Kr krypton 84 54 Xe xenon 131 86 Rn radon – 118 Og oganesson – 21 Sc scandium 45 39 Y yttrium 89 57–71 lanthanoids 89–103 actinoids 57 La lanthanum 139 89 Ac lanthanoids actinoids The volume of one mole of any gas is 24 dm3 at room temperature and pressure (r.t.p.). actinium – 58 Ce cerium 140 90 Th thorium 232 59 Pr praseodymium 141 91 Pa protactinium 231 60 Nd neodymium 144 92 U uranium 238 61 Pm promethium – 93 Np neptunium – 62 Sm samarium 150 94 Pu plutonium – 63 Eu europium 152 95 Am americium – 64 Gd gadolinium 157 96 Cm curium – 65 Tb terbium 159 97 Bk berkelium – 66 Dy dysprosium 163 98 Cf californium – 67 Ho holmium 165 99 Es einsteinium – 68 Er erbium 167 100 Fm fermium – 69 Tm thulium 169 101 Md mendelevium – 70 Yb ytterbium 173 102 No nobelium – 71 Lu lutetium 175 103 Lr lawrencium –

This document consists of 3 printed pages. © Cambridge University Press & Assessment 2025 [Turn over Cambridge IGCSE™ (9–1) CHEMISTRY (9–1) 0971/21 Paper 2 Multiple Choice (Extended) May/June 2025 MARK SCHEME Maximum Mark: 40 Published This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the examination. Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for Teachers. Cambridge International will not enter into discussions about these mark schemes. Cambridge International is publishing the mark schemes for the May/June 2025 series for most Cambridge IGCSE, Cambridge International A and AS Level components, and some Cambridge O Level components.

0971/21 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 Page 2 of 3 Question Answer Marks 1 A 1 2 D 1 3 D 1 4 B 1 5 C 1 6 B 1 7 C 1 8 D 1 9 A 1 10 C 1 11 B 1 12 A 1 13 C 1 14 D 1 15 D 1 16 B 1 17 B 1 18 D 1 19 A 1 20 B 1 21 C 1 22 C 1 23 A 1 24 D 1 25 A 1 26 B 1 27 A 1 28 C 1

0971/21 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 Page 3 of 3 Question Answer Marks 29 C 1 30 A 1 31 B 1 32 A 1 33 B 1 34 C 1 35 C 1 36 D 1 37 B 1 38 D 1 39 C 1 40 D 1