Chemistry 0620/21 May/June 2025: question paper and mark scheme

Question

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

Question

A sample of ethanol is heated at a constant rate. The heating curve for this sample is shown. 6 4 5 temperature 2 3 1 time 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.

Question

Which atom has an equal number of protons, neutrons and electrons? 40 1 23 14 A Ar B H C Na D N

Question

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%

Question

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.

Question

Which dot-and-cross diagram shows the outer shell electron arrangement in a molecule of nitrogen? A B N N N N C D N N N N

Question

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.

Question

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

Question

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

Question

The diagram shows the electroplating of a steel object. + power – supply steel object copper electrode aqueous copper(II) sulfate 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

Question

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

Question

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

Question

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 reactants energy A endothermic products progress of reaction products energy B endothermic reactants progress of reaction reactants energy C exothermic products progress of reaction products energy D exothermic reactants progress of reaction

Question

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

Question

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. 50 °C total volume of 30 °C carbon dioxide given off / cm3 0 0 time / s Which row describes the reacting particles at 30 °C compared to those at 50 °C? frequency average of collisions kinetic energy between particles of particles A higher higher B higher lower C lower higher D lower lower

Question

Industrially, ammonia is made by the Haber process. The equation is shown. N2(g) + 3H2(g) 2NH3(g) ΔH = –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

Question

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

Question

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.

Question

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

Question

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

Question

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.

Question

Which property decreases down Group VII of the Periodic Table, from chlorine to iodine? A atomic number B density C reactivity D melting point

Question

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

Question

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.

Question

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.

Question

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

Question

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.

Question

Which process is used in the extraction of iron from hematite? A electrolysis B precipitation C reduction D fractional distillation

Question

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

Question

Nitrogen, phosphorus and potassium are essential elements for improved plant growth. Which mixture provides all three essential elements? mixture formulae A ammonium phosphate (NH4)3PO4 + + potassium chloride KCl B ammonium phosphate (NH4)3PO4 + + ammonium nitrate NH4NO3 C ammonium phosphate (NH4)3PO4 + + ammonium chloride NH4Cl D ammonium nitrate NH4NO3 + + potassium chloride KCl

Question

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

Question

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.

Question

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

Question

What is the total number of covalent bonds in one molecule of propane? A 8 B 9 C 10 D 11

Question

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

Question

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

Question

The structures of two monomers that are used to make a condensation polymer are shown. O O H H H C C HO C C C OH HO OH H H H Which structure represents one repeat unit of the condensation polymer formed? A B O O H H H O O H H H C C C C C C C O C C C O H H H H H H C D O H H H O O H O H H C O C C C C O C C C O C C O H H H H H H

Question

Which item of apparatus is used to measure 25.0 cm3 of aqueous sodium hydroxide? A B C D

Question

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

Question

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. 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.).