Chemistry 0620/23 May/June 2025: question paper and mark scheme

Question

Which two changes, when applied at the same time to a fixed amount of gas, cause the greatest increase in volume of the gas? change in pressure change in temperature A decrease by 10% decrease by 10% B increase by 10% decrease by 10% C decrease by 20% increase by 10% D increase by 20% increase by 10%

Question

Solid G is heated until it melts. It is then left to cool to room temperature. The graph shows the cooling curve for G. temperature X Y time Four statements about the cooling curve between X and Y are listed. 1 The speed of the molecules of G decreases. 2 The molecules of G become less closely packed. 3 Thermal energy is released by the molecules of G to the surroundings. 4 G changes from solid to liquid. Which statements are correct? A 1 and 2 B 1 and 3 C 2 and 4 D 3 and 4

Question

Which atom has twice as many neutrons as protons? 1 2 3 4 A 1H B 1H C 1H D 2 He

Question

What is the nucleon number of an atom? A the number of electrons, neutrons and protons in the nucleus B the number of neutrons and protons in the nucleus C the number of neutrons in the nucleus D the number of protons in the nucleus

Question

The diagram shows the positions of elements P and Q in the Periodic Table. Q P What is the formula of the compound that is formed between P and Q? A PQ B P2Q C PQ2 D P2Q7

Question

Which statement about ionic compounds is correct? A Giant lattices are formed when ionic compounds crystallise from solution. B In all ionic compounds, the metal ions have fewer electrons than the non-metal ions. C In a giant lattice, ions of the same charge are closer together than ions of opposite charge. D When ionic compounds melt, strong intermolecular forces are broken.

Question

The equation for the reaction between iron(III) chloride and sodium hydroxide is shown. FeCl 3(aq) + 3NaOH(aq) → Fe(OH)3(s) + 3NaCl (aq) What is the ionic equation for this reaction? A Fe3+(aq) + 3OH–(aq) → Fe3+(s) + 3OH–(s) B Fe3+(aq) + 3OH–(aq) → Fe(OH)3(s) C 3Na+(aq) + 3Cl –(aq) → 3Na+(aq) + 3Cl –(aq) D 3Na+(aq) + 3Cl –(aq) → 3NaCl (aq)

Question

A compound is analysed and found to contain 85.7% carbon and 14.3% hydrogen only. What is its empirical formula? A CH B CH2 C C2H4 D C6H

Question

Aqueous barium hydroxide, Ba(OH)2, reacts with dilute nitric acid, HNO3. The products are aqueous barium nitrate, Ba(NO3)2, and water. In a titration, 15.2 cm3 of 0.75 mol / dm3 aqueous barium hydroxide is required to neutralise 20.0 cm3 of dilute nitric acid. What is the concentration of the nitric acid? A 0.29 mol / dm3 B 0.57 mol / dm3 C 1.14 mol / dm3 D 2.03 mol / dm3

Question

Which particles are responsible for the transfer of charge in the external circuit during the electrolysis of molten lead(II) bromide? A anions B atoms C cations D electrons

Question

Two statements about hydrogen are listed. 1 Hydrogen is used as a fuel. 2 When hydrogen burns in the air to form water, thermal energy is produced. Which conclusion about these statements is 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

Concentrated aqueous copper(II) chloride is electrolysed using carbon electrodes. What is formed at each electrode? negative electrode positive electrode A chlorine copper B copper chlorine C copper oxygen D oxygen copper

Question

Which row describes an exothermic reaction? sign of enthalpy temperature of change, ΔH the surroundings A positive decreases B positive increases C negative decreases D negative increases

Question

A reaction pathway diagram is shown. products X energy Y reactants progress of reaction Which row shows the correct labels for X and Y and the type of reaction taking place? X Y type of reaction A enthalpy change activation energy exothermic B activation energy enthalpy change endothermic C activation energy enthalpy change exothermic D enthalpy change activation energy endothermic

Question

The rate of reaction between magnesium and dilute hydrochloric acid is increased by increasing the concentration of the acid. How does this affect the reacting particles? proportion of particles with collision rate of particles sufficient energy to react A increases increases B increases stays the same C stays the same increases D stays the same stays the same

Question

The reaction between aqueous iron(III) ions, Fe3+, and aqueous thiocyanate ions, SCN–, is reversible. The equation for the reaction is shown. Fe3+(aq) + SCN–(aq) FeSCN2+(aq) yellow colourless red At equilibrium, the concentrations of Fe3+ ions, SCN– ions, and FeSCN2+ ions are identical, and the mixture appears orange. When a few drops of aqueous thiocyanate ions are added to the mixture, a new equilibrium forms. How does the colour of the mixture change? A It becomes colourless. B It becomes a lighter orange. C It becomes more yellow. D It becomes more red.

Question

The equation for the reaction between iron(II) sulfate and bromine is shown. 6FeSO4 + 3Br2 → 2Fe2(SO4)3 + 2FeBr3 Which row identifies the oxidising agent and the reducing agent? oxidising agent reducing agent A Br2 FeSO4 B FeSO4 Br2 C FeBr3 Fe2(SO4)3 D Fe2(SO4)3 FeBr3

Question

The equation represents a redox reaction. 2Al + Fe2O3 → 2Fe + Al 2O3 What is the change in the oxidation number of iron in this reaction? A from +2 to +3 B from +2 to 0 C from +3 to +2 D from +3 to 0

Question

Aqueous ammonia forms an equilibrium with water. NH3 + H2O NH4+ + OH– In this equilibrium, which particle acts as an acid and which particle acts as a base? acid base A NH3 H2O B NH3 OH– C H2O NH3 D H2O NH4+

Question

Which row identifies an acidic oxide, a basic oxide and an amphoteric oxide? acidic basic amphoteric A ZnO SO2 Al 2O3 B SO2 Al 2O3 Na2O C ZnO Al 2O3 SO2 D SO2 Na2O Al 2O3

Question

A Group I metal (lithium or potassium) is reacted with a Group VII element (chlorine or iodine). Which compound is formed when the Group I metal of highest density reacts with the Group VII element of lowest density? A potassium chloride B lithium chloride C potassium iodide D lithium iodide

Question

Element X is in the same group of the Periodic Table as silicon. An atom of element X has more protons than a silicon atom. Which element could be X? A aluminium B carbon C germanium D phosphorus

Question

Which statement about the elements in Group VIII is correct? A They all form diatomic molecules. B They all have eight electrons in their outer electron shells. C They all react with oxygen to form oxides. D They all are gases at room temperature.

Question

Which element is a transition element? melting point density at r.t.p. colour of oxide in °C in g / cm3 at r.t.p. A 98 1.0 white B 328 11.3 yellow C 651 1.7 white D 1907 7.2 green

Question

Four test-tubes contain dilute hydrochloric acid. Each test-tube has one piece of a different metal added to it. The metals are copper, iron, magnesium and zinc. Which test-tube contains iron and dilute hydrochloric acid? A B C D

Question

Brass is a mixture of copper and zinc. Which statement describes and explains the relative strength of brass compared to copper? A Brass is stronger than copper because the layers of atoms in brass cannot easily slide over each other. B Brass is stronger than copper because the intermolecular forces are greater in brass than in copper. C Brass is weaker than copper because the layers of atoms slide more easily over each other in brass than in copper. D Brass is weaker than copper because the intermolecular forces are weaker in brass than in copper.

Question

A sample of calcium carbonate is heated strongly, and substances U and V are formed. Substance U is a white solid. Substance V is a colourless gas. What are substances U and V? U V A calcium chloride oxygen B calcium hydroxide carbon dioxide C calcium oxide carbon dioxide D calcium sulfate oxygen

Question

A sample of water taken from a river contains harmful microbes. What is a source of harmful microbes in the river water? A sewage B fertilisers C detergents D plastics

Question

Anhydrous copper(II) sulfate and anhydrous cobalt(II) chloride change colour when water is added to them. Which row shows the correct colour changes? copper(II) sulfate cobalt(II) chloride A blue to white blue to pink B blue to white pink to blue C white to blue blue to pink D white to blue pink to blue

Question

Which gas contributes to increased global warming? A argon B carbon dioxide C nitrogen D oxygen

Question

Which statement describes how greenhouse gases increase global warming? A Greenhouse gases absorb thermal energy from the Sun, reducing the Earth’s temperature. B Greenhouse gases reflect thermal energy back into space, cooling the Earth’s surface. C Greenhouse gases absorb and re-emit thermal energy radiated from the Earth’s surface. D Greenhouse gases release thermal energy from the Earth into space.

Question

Nitrogen monoxide is produced in a car engine when petrol is burned. The gases from the car engine are passed through a catalytic converter. In the catalytic converter, the nitrogen monoxide, NO, reacts with carbon monoxide, CO, to form nitrogen and carbon dioxide. Which statement is not correct? A Carbon monoxide is oxidised in the catalytic converter. B Carbon monoxide is produced by the complete combustion of petrol. C Nitrogen monoxide is formed by the reaction of nitrogen and oxygen. D Nitrogen monoxide is reduced in the catalytic converter.

Question

The displayed formula of but-2-ene is shown. H H H H H C C C C H H H Which displayed formulae represent structural isomers of but-2-ene? H H H H H H H H H H C H H C C C H H C C C C H C C H H H C H H H H H C H H H 1 2 3 A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Question

Which row describes two characteristics of members of the same homologous series? characteristic 1 characteristic 2 A same functional group trend in physical properties B same physical properties same functional group C same general formula different chemical properties D differing from one member similar chemical properties to the next by a CH3 unit

Question

Compound W is a hydrocarbon that contains single bonds only. Which homologous series contains W? A alkenes B alkanes C carboxylic acids D alcohols

Question

Methane forms chloromethane in a photochemical reaction using ultraviolet light. Which statement about this reaction is correct? A Methane is mixed with hydrogen chloride gas, and ultraviolet light prevents a combustion reaction. B Methane is mixed with hydrogen chloride gas, and ultraviolet light provides the activation energy for the reaction. C Methane is mixed with chlorine gas, and ultraviolet light prevents a combustion reaction. D Methane is mixed with chlorine gas, and ultraviolet light provides the activation energy for the reaction.

Question

Which statement about polymers is correct? O A Nylon contains the C N linkage. H B Nylon is a polyester. C Propane can be polymerised by addition polymerisation. D The linkage in PET contains a carbon–carbon double bond.

Question

The steps used to separate a mixture of a soluble solid and an insoluble solid are listed. ● A solution is made by adding the mixture to a suitable ……1…… . ● The mixture is stirred and then poured through a filter funnel lined with filter paper. ● The insoluble solid is collected on the filter paper as the ……2…… . Which words complete gaps 1 and 2? 1 2 A solute filtrate B solute residue C solvent filtrate D solvent residue

Question

Which items of apparatus are used to separate a mixture of liquids with different boiling points? A B C D power supply – +

Question

In paper chromatography, what is the equation for the Rf value? distance travelled by solvent A Rf = distance travelled by substance distance travelled by locating agent B Rf = distance travelled by substance distance travelled by substance C Rf = distance travelled by locating agent distance travelled by substance D Rf = distance travelled by solvent 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.).