Chemistry 0620/23 October/November 2025: question paper and mark scheme

Question

What happens to the volume of a fixed mass of gas when pressure and temperature are separately increased? volume of gas pressure temperature increased increased A increases increases B no change decreases C decreases increases D no change increases

Question

Which gas diffuses most quickly at room temperature and pressure? A CH4 B C2H6 C CO D SO2

Question

Which statement defines nucleon number? A It is the total number of protons in the nucleus of an atom. B It is the total number of electrons surrounding the nucleus of an atom. C It is the total number of neutrons in the nucleus of an atom. D It is the total number of protons and neutrons in the nucleus of an atom.

Question

The symbols of four atoms are listed. 12 1 6C 14 2 6C 14 3 7N 29 4 14 Si Which atoms have more neutrons than protons? A 1 and 2 B 2 and 3 C 2 and 4 D 3 and 4

Question

Which statement describes all positive ions? A Positive ions have more electrons than neutrons. B Positive ions have more protons than neutrons. C Positive ions have more electrons than protons. D Positive ions have more protons than electrons.

Question

A sample of copper has a relative atomic mass of 63.5. What are the relative abundances of the isotopes in this sample of copper? A 25% 63Cu and 75% 65Cu B 50% 63Cu and 50% 65Cu C 75% 63Cu and 25% 65Cu D 90% 63Cu and 10% 65Cu

Question

Which diagram shows the outer shell electron arrangement for a molecule of methanol, CH3OH? A B H H H C O H H C O H H H C D H H H C O H H C O H H H

Question

Rescuers are drilling through fallen rock in order to rescue some people trapped in a cave. The drill needs lubricating from time to time. Four statements are made about the materials used for the drill tip and the lubricant to explain the reasons for their use. 1 Diamond is used for the drill tip as it does not conduct electricity. 2 Diamond is used for the drill tip as it is very hard. 3 Graphite is used as the lubricant as it conducts electricity. 4 Graphite is used as the lubricant as it is soft and slippery. Which statements are correct? A 1 and 3 B 1 and 4 C 2 and 3 D 2 and 4

Question

Which compound has an empirical formula that is the same as its molecular formula? A butane B but-1-ene C butanoic acid D butan-1-ol

Question

Which row identifies the charge on the chromium ion and on the sulfate ion in Cr2(SO4)3? Cr SO4 A 2+ 3– B 2– 3+ C 3+ 2– D 3– 2+

Question

Which statement describes a saturated solution? A It is a solution that contains the maximum concentration of solute. B It is a solution that contains the maximum amount of solvent. C It is a hydrocarbon that contains both double and single bonds. D It is a hydrocarbon that contains only single bonds.

Question

Calcium carbonate decomposes when heated strongly. CaCO3(s) → CaO(s) + CO2(g) How many gaseous molecules are produced when 10.0 g of calcium carbonate is completely decomposed? A 1.00 × 1022 B 1.20 × 1023 C 6.02 × 1022 D 6.02 × 1023

Question

Which product is initially obtained at each electrode during the electrolysis of concentrated aqueous sodium chloride? cathode anode A hydrogen chlorine B hydrogen oxygen C sodium chlorine D sodium oxygen

Question

Molten lead(II) bromide is electrolysed using inert electrodes. power supply X + – Y Which statement describes the movement of electrons? A from X to Y through the external wire B from Y to X through the external wire C from X to Y through the electrolyte D from Y to X through the electrolyte

Question

In a fuel cell, a fuel is oxidised to produce electricity. Which row describes the fuel and the oxidising agent used? fuel oxidising agent A nitrogen oxygen B hydrogen oxygen C nitrogen water D hydrogen water

Question

Which statement about reactions is correct? A A reaction that is vigorous at room temperature has a high activation energy. B If ΔH for a reaction is positive, bond making in the formation of the products is endothermic. C In an exothermic reaction, the energy required to break bonds is less than the energy released to make bonds. D Reactions with a positive enthalpy change always transfer thermal energy to the surroundings.

Question

Ethene reacts with hydrogen to form ethane. H H H H C C + H H o H C C H H H H H The bond energies are shown in the table. bond energy bond in kJ / mol C–C +350 C–H +410 H–H +436 C=C +614 What is the enthalpy change for the reaction? A –290 kJ / mol B –120 kJ / mol C +120 kJ / mol D +290 kJ / mol

Question

Zinc reacts with dilute hydrochloric acid. Which statement about the particles in the reaction is correct? A Increasing the concentration of dilute hydrochloric acid increases the collision rate but has no effect on the activation energy. B Increasing the concentration of dilute hydrochloric acid increases the collision rate and the activation energy. C Increasing the temperature of the reaction increases the activation energy. D Increasing the temperature of the reaction causes all collisions to lead to a reaction.

Question

Ethanol is manufactured by the addition of steam to ethene. C2H4(g) + H2O(g) C2H5OH(g) The reaction conditions are 300 °C and 60 atm. The forward reaction is exothermic. Which rows describe the effect on the equilibrium yield of C2H5OH when the stated change is made? equilibrium change yield of C2H5OH 1 adding a catalyst no change 2 decreasing the temperature increases 3 decreasing the pressure increases A 1 and 2 B 1 and 3 C 2 only D 3 only

Question

Which row identifies the conditions used to make sulfur trioxide in the Contact process? pressure / kPa catalyst A 200 iron B 200 vanadium(V) oxide C 20 000 iron D 20 000 vanadium(V) oxide

Question

Which statement describes a base? A It reacts with ammonium chloride to produce ammonia gas. B It reacts with calcium carbonate to produce carbon dioxide gas. C It reacts with copper to produce hydrogen gas. D It turns blue litmus red.

Question

The equation shows the reaction between copper and concentrated nitric acid. Cu(s) + 4HNO3(aq) → Cu(NO3)2(aq) + 2NO2(g) + 2H2O(l) Which element is reduced in this reaction? A oxygen B nitrogen C copper D hydrogen

Question

The Periodic Table shows the position of four different elements. A B C D Which row is correct? number of electrons element in the outer shell A non-metal 1 B metal 5 C metal 2 D non-metal 7

Question

Dilute acid R and dilute acid S have the same concentration. The same volume of each dilute acid is reacted separately with the same mass of magnesium ribbon. Both reactions are carried out at room temperature and pressure. The volume of hydrogen produced is measured. A graph of the results is shown. total volume R of hydrogen S 0 0 time Which statement about the reactions is correct? A Acid S reacts faster than acid R. B The final volume of hydrogen produced in each reaction is different. C Acid R is a stronger acid than acid S. D Acid S is a stronger acid than acid R.

Question

Which metal oxide reacts with aqueous sodium hydroxide to form a salt and water? A calcium oxide B copper(II) oxide C sodium oxide D aluminium oxide

Question

Which row identifies a transition element? melting point density at r.t.p. A high high B high low C low high D low low

Question

Which statement about Group I or Group VII elements is correct? A Group VII elements are monatomic non-metals. B Lithium is more reactive with water than caesium. C The melting point of Group I metals increases down the group. D Potassium bromide reacts with chlorine to produce an orange solution.

Question

Some information about four metals P, Q, R and S is listed. Metal P does not react with dilute hydrochloric acid. Metal Q is more reactive than magnesium. Metal R reacts rapidly with cold water to produce hydrogen. Metal S reacts with dilute hydrochloric acid to produce hydrogen. Which row identifies P, Q, R and S? P Q R S A gold aluminium sodium copper B copper potassium calcium magnesium C silver calcium iron zinc D magnesium sodium potassium iron

Question

Cars are fitted with catalytic converters. Which equation represents a reaction that takes place in a catalytic converter? A CO2 + NO2 → CO + NO + O2 B 2CO + 2NO → 2CO2 + N2 C CO2 + N2 → C + 2NO D C + NO2 → CO + NO

Question

Three statements about greenhouse gases and global warming are listed. 1 A greenhouse gas molecule can absorb and emit thermal energy. 2 The Earth is a source of thermal energy. 3 Thermal energy emitted by a greenhouse gas molecule is sent out in all directions. 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

Which type of reaction takes place when methane reacts with chlorine in the presence of ultraviolet light? A addition B cracking C polymerisation D substitution

Question

Iron is extracted from iron(III) oxide in the blast furnace. Three steps in the process are listed. 1 Carbon (coke) is completely oxidised. 2 Iron(III) oxide is reduced. 3 Carbon dioxide is reduced to carbon monoxide. What is the correct order of the steps in the extraction of iron? A 1→2→3 B 1→3→2 C 2→1→3 D 3→1→2

Question

Three different reactions that occur during the extraction of aluminium from purified bauxite are listed. 1 Al 3+ + 3e– → Al 2 C + O2 → CO2 3 2O2– → O2 + 4e– Which reactions occur at the anode? A 1 and 2 B 1 only C 2 and 3 D 3 only

Question

Which statement about aqueous ethanoic acid is correct? A It reacts with magnesium to form oxygen gas. B It reacts with sodium carbonate to form carbon dioxide gas. C It turns red litmus paper blue. D It turns methyl orange yellow.

Question

The diagrams represent four monomers. H 2N NH2 HOOC NH2 HO NH2 HO OH The monomers each react in a 1 : 1 ratio with the dicarboxylic acid shown. HOOC COOH How many of the four monomers shown can react with the dicarboxylic acid to form a polymer? A 1 B 2 C 3 D 4

Question

Propene undergoes addition reactions with bromine, hydrogen and steam. Which structures represent a product of these reactions? Br H Br H Br H H H H H OH H H C C C H H C C C H H C C C H H C C C H H H H H H H H H H H H H 1 2 3 4 A 1 and 3 B 1 and 4 C 2 and 3 D 3 and 4

Question

The structures of four compounds are shown. H H H H H H H H H H C C H C C H C C O H H C C C H H H H H H H H H H 1 2 3 4 Which compounds are members of the same homologous series? A 1, 2 and 3 B 1 and 2 only C 1 and 4 D 2 and 4

Question

Which statement about ethanoic acid is correct? A Ethanol is reduced by bacteria to produce ethanoic acid. B Ethanoic acid reacts with magnesium to produce a salt of formula CH3COOMg. C Ethanoic acid and methanol react in the presence of an acid catalyst to produce ethyl methanoate. D Ethanol reacts with acidified aqueous potassium manganate(VII) to produce ethanoic acid.

Question

Substance X contains one cation. Two tests are completed on aqueous X. test 1 flame test test 2 addition of aqueous sodium hydroxide dropwise and then in excess Which row shows a possible combination of observations for the tests? observation for test 1 observation for test 2 A yellow flame white ppt., insoluble in excess B blue-green flame light blue ppt., insoluble in excess C light green flame green ppt., soluble in excess D red flame red-brown ppt., insoluble in excess

Question

A colourless mixture is separated by paper chromatography. The steps below describe the method. These steps are not in the correct order. 1 Remove the chromatography paper from the solvent when the solvent front is near the top of the paper. 2 Place the chromatography paper in the solvent. 3 Spray the chromatography paper with a locating agent. 4 Place a spot of the mixture on the pencil line. 5 Draw a pencil line at the bottom of the chromatography paper. 6 Draw a pencil line to mark the position of the solvent front. What is the correct order for these steps? A 3→5→6→4→2→1 B 5→4→3→2→1→6 C 3→5→4→1→2→6 D 5→4→2→1→6→3 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.).