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Practice paper written from an analysis of every
O-Level Science (Chemistry) paper, 2010–2025
Paper 3 Chemistry
FORECAST PAPER · PAPER 3.9
For practice before the 2026 examination
1 hour 15 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
Write your name, centre number and index number in the boxes above.
You may use an HB pencil for any diagrams, graphs or rough working.
Write in dark blue or black pen.
Do not use staples, paper clips, glue or correction fluid.
The use of an approved scientific calculator is expected, where appropriate.
You may lose marks if you do not show your working or if you do not use appropriate units.
Section A
Answer all questions.
Write your answers in the spaces provided on the question paper.
Section B
Answer one question.
Write your answers in the spaces provided on the question paper.
A copy of the Data Sheet is printed on page 17.
A copy of the Periodic Table is printed on page 18.
The number of marks is given in brackets [ ] at the end of each question or part question.
The total mark for this paper is 65.
A mining company refines zinc, tin and lead. Technicians measure the melting point and the boiling point of three samples, P, Q and R, and compare them with the values for the pure metals in Table 1.1. The letters are not the chemical symbols.
| metal | melting point / °C | boiling point / °C |
|---|---|---|
| zinc | 420 | 907 |
| tin | 232 | 2602 |
| lead | 327 | 1749 |
Complete Table 1.2.
| sample | melting point / °C | boiling point / °C | metal present | pure or impure |
|---|---|---|---|---|
| P | 232 | 2602 | pure | |
| Q | 300 to 318 | 1755 to 1772 | lead | |
| R | 420 | 907 | pure |
Table 2.1 shows the numbers of protons, neutrons and electrons in six particles, A to F, found in rocks that are mined for metals. The letters are not the chemical symbols.
| particle | number of protons | number of neutrons | number of electrons |
|---|---|---|---|
| A | 30 | 35 | 30 |
| B | 30 | 34 | 30 |
| C | 30 | 35 | 28 |
| D | 53 | 74 | 54 |
| E | 50 | 69 | 48 |
| F | 34 | 45 | 36 |
Use the letters A to F to answer the questions. Each letter can be used once, more than once or not at all.
Identify the particle which:
is a positive ion that contains 28 electrons
is a negative ion with a charge of 1−
has a nucleon number of 119
Identify the two atoms that are isotopes of the same element.
A student writes four statements, A, B, C and D, about materials that are used in transport and in mining. Table 3.1 shows the statements.
| letter | statement |
|---|---|
| A | Silver is used in electrical switches on trains because it has a low melting point. |
| B | Road salt, sodium chloride, conducts electricity when it is molten but not when it is solid. |
| C | Butane, a fuel for taxis, has a low boiling point because only weak forces between its molecules have to be overcome. |
| D | The aluminium alloy used to build aircraft is a compound, because it contains aluminium and other elements. |
Two of the statements are not correct.
Write the letters of the two statements that are not correct.
Correct the two statements.
Write a correct statement about the melting points of metals such as silver.
Write a correct statement about the aluminium alloy.
Statement B is correct.
Explain why sodium chloride conducts electricity when it is molten but not when it is solid.
Oxides can be acidic, basic, amphoteric or neutral.
Choose from the oxides listed to answer (a).
Each oxide can be used once, more than once or not at all.
Identify the oxide which:
is amphoteric
is a neutral oxide
reacts with dilute hydrochloric acid but does not react with aqueous sodium hydroxide
Water that drains from an abandoned metal mine is acidic. It has a pH of 3.
A company adds calcium hydroxide, an alkali, to the water to neutralise it.
Write an ionic equation for the neutralisation reaction.
Explain why the pH of the water increases when calcium hydroxide is added.
Aluminium, made from the ore bauxite, is used to build aircraft and trains. It reacts with dilute hydrochloric acid to form aluminium chloride and hydrogen.
A student investigates how temperature affects the rate of this reaction. The student warms 50 cm3 of dilute hydrochloric acid, 1.0 mol / dm3, in the flask in Fig. 5.1, adds 0.20 g of aluminium powder, closes the flask with the bung and records the time taken to collect 40 cm3 of gas in the gas syringe. The student does the experiment twice at each of four temperatures. Table 5.1 shows the results.
| temperature / °C | time in experiment 1 / s | time in experiment 2 / s |
|---|---|---|
| 20 | 150 | 156 |
| 30 | 82 | 80 |
| 40 | 41 | 63 |
| 50 | 22 | 21 |
Identify the anomalous result in Table 5.1.
Suggest what the student should do to obtain more reliable results.
The time taken is much shorter at 50 °C than at 20 °C.
Explain why. Use ideas about particles in your answer.
Burning magnesium, used in railway flares, gives out heat and light.
Name the type of reaction that gives out heat to the surroundings.
Fig. 6.1 shows the concentration of nitrogen dioxide measured at a monitoring station beside a busy road in a city, on a weekday and on a Sunday. The unit ppb means parts per billion.
Use Fig. 6.1 to calculate the difference between the concentrations on a weekday and on a Sunday at 18:00.
Nitrogen dioxide is formed in vehicle engines.
Suggest why the concentration at 18:00 is higher on a weekday than on a Sunday.
State one harmful effect of nitrogen dioxide on the environment.
Most of the buses in the city burn diesel. Diesel is separated from crude oil by a process that depends on the different boiling points of the hydrocarbons.
Name this process.
The city plans to run some buses on bioethanol, made from sugar cane.
Explain why burning bioethanol increases the total amount of carbon dioxide in the air by less than burning diesel. Use ideas about photosynthesis.
A technician tests mine water for ions. Some of the tests give off a gas. Table 7.1 shows some tests for ions and gases.
| ion or gas | reagent | positive result |
|---|---|---|
| copper(II) ion | aqueous sodium hydroxide | |
| iron(III) ion | red-brown precipitate | |
| aqueous ammonia, added until in excess | white precipitate that dissolves in excess | |
| sulfate ion | white precipitate | |
| chloride ion | dilute nitric acid, then aqueous silver nitrate | |
| ammonia gas | litmus paper turns blue | |
| carbon dioxide gas | limewater |
Complete Table 7.1.
Mine water that contains copper(II) ions is mixed with aqueous sodium hydroxide.
Write an ionic equation, including state symbols, for the reaction that forms the precipitate.
Methane, CH4, is a gas that collects in coal mines. It is called firedamp. It burns in air and can cause explosions.
A sample of 50 cm3 of methane burns completely. All gas volumes are measured at room temperature and pressure.
Calculate the relative molecular mass, Mr, of water.
Calculate the volume of oxygen needed to burn 50 cm3 of methane.
Calculate the volume of carbon dioxide formed.
Calculate the volume of air that contains the volume of oxygen in (b).
Calculate the mass of water formed when 50 cm3 of methane burns.
Use your answer to (a).
Kerosene is a fraction of crude oil that is used as aircraft fuel. Fig. 9.1 shows how a hydrocarbon in kerosene can be used to make other useful substances. The letters are not the chemical symbols.
Complete Fig. 9.1 by writing the formula or the name of B, C, D and G, and the name of process F.
Poly(ethene) is formed when many molecules of ethene join together.
Explain why ethane, C2H6, cannot form a polymer in the same way.
State the colour change when ethene is bubbled through aqueous bromine.
Cracking is essential in an oil refinery.
Suggest why.
Name the type of reaction that forms C from ethene.
Argon is a gas that is used to shield the hot metal when railway tracks and aircraft parts are welded. Argon, sodium and sulfur are all in Period 3 of the Periodic Table.
Table 10.1 shows five elements in Period 3.
| element | proton number | electronic configuration |
|---|---|---|
| sodium | 11 | 2.8.1 |
| magnesium | 12 | 2.8.2 |
| sulfur | 16 | 2.8.6 |
| chlorine | 17 | 2.8.7 |
| argon | 18 | 2.8.8 |
Five students make statements about the Periodic Table. Four of the statements are in Table 10.2.
Put one tick in each row of Table 10.2 to show whether the statement is correct or not correct.
| student | statement | correct | not correct |
|---|---|---|---|
| Aisha | The elements in the Periodic Table are arranged in order of increasing nucleon number. | ||
| Ben | Sodium, magnesium and sulfur are in Period 3 because their atoms each have three electrons in the outer shell. | ||
| Chen | Across Period 3, from sodium to chlorine, the elements change from metallic to non-metallic. | ||
| Dee | Argon is unreactive because its atoms each have one electron in the outer shell. |
Aisha's statement is not correct. Correct her statement.
Use Table 10.1 to correct Ben's statement.
Dee's statement is not correct. Correct her statement.
Use Table 10.1 and the Periodic Table to answer the questions.
Phosphorus has proton number 15. State the electronic configuration of a phosphorus atom.
An element in Period 3 has the electronic configuration 2.8.3. Name this element.
Sodium reacts with sulfur to form sodium sulfide, Na2S, an ionic compound. Draw a 'dot-and-cross' diagram to show the bonding in sodium sulfide. Show only the outer shell electrons. Include the charge on each ion.
Fran makes the fifth statement. The equation for the reaction of sodium with sulfur is shown.
Metals used in transport, such as the iron in railway tracks and the copper in overhead cables, are obtained from ores that are mined.
A chemist tests four metals, W, X, Y and Z. Each metal is added to dilute hydrochloric acid. The oxide of each metal is also heated with carbon. Table 11.1 shows the results. The letters are not the chemical symbols.
| metal | added to dilute hydrochloric acid | oxide of the metal heated with carbon |
|---|---|---|
| W | bubbles form very rapidly | no change |
| X | bubbles form steadily | the metal forms when heated very strongly |
| Y | no bubbles | the metal forms when heated gently |
| Z | bubbles form slowly | the metal forms when heated strongly |
Fig. 11.1 is a reactivity diagram for these four metals and for calcium and silver. It is incomplete.
Use Table 11.1 to complete Fig. 11.1. Write the letters W, X, Y and Z in the empty boxes.
The metals X, Y and Z are copper, iron and zinc, but not in this order. Identify X, Y and Z.
A mining company cannot obtain metal W by heating its oxide with carbon. Use Table 11.1 to explain why.
The line on the right of Fig. 11.1 is labelled “ease of obtaining the metal from its ore”. Draw an arrowhead on this line to show the direction in which it becomes easier to obtain the metal.
Metal V reacts with dilute hydrochloric acid. The oxide of V is reduced by carbon when it is heated gently.
Choose the place in Fig. 11.1 where V should be put. Circle one letter.
Give a reason for your answer to (i). Use Table 11.1.
Nitrogen gas, N2, is used to inflate the tyres of aircraft. Fig. 11.2 shows four 'dot-and-cross' diagrams, A, B, C and D, for a molecule of nitrogen. Only the outer shell electrons are shown.
Identify the diagram that shows a molecule of nitrogen correctly.
Give one reason why diagram B is not correct.
Copper is obtained by heating copper(II) oxide with carbon. The equation for the reaction is shown.
| aluminium hydroxide | white |
| calcium hydroxide | white |
| copper(II) hydroxide | light blue |
| iron(II) hydroxide | green |
| iron(III) hydroxide | red-brown |
| zinc hydroxide | white |
Group | |||||||||||||||||
1 | 2 |
| 13 | 14 | 15 | 16 | 17 | 18 | |||||||||
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| 1 H hydrogen 1 |
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| 2 He helium 4 | ||
3 Li lithium 7 | 4 Be beryllium 9 |
| proton (atomic) number atomic symbol name relative atomic mass |
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| 5 B boron 11 | 6 C carbon 12 | 7 N nitrogen 14 | 8 O oxygen 16 | 9 F fluorine 19 | 10 Ne neon 20 | ||
11 Na sodium 23 | 12 Mg magnesium 24 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 Al aluminium 27 | 14 Si silicon 28 | 15 P phosphorus 31 | 16 S sulfur 32 | 17 Cl chlorine 35.5 | 18 Ar argon 40 |
19 K potassium 39 | 20 Ca calcium 40 | 21 Sc scandium 45 | 22 Ti titanium 48 | 23 V vanadium 51 | 24 Cr chromium 52 | 25 Mn manganese 55 | 26 Fe iron 56 | 27 Co cobalt 59 | 28 Ni nickel 59 | 29 Cu copper 64 | 30 Zn zinc 65 | 31 Ga gallium 70 | 32 Ge germanium 73 | 33 As arsenic 75 | 34 Se selenium 79 | 35 Br bromine 80 | 36 Kr krypton 84 |
37 Rb rubidium 85 | 38 Sr strontium 88 | 39 Y yttrium 89 | 40 Zr zirconium 91 | 41 Nb niobium 93 | 42 Mo molybdenum 96 | 43 Tc technetium – | 44 Ru ruthenium 101 | 45 Rh rhodium 103 | 46 Pd palladium 106 | 47 Ag silver 108 | 48 Cd cadmium 112 | 49 In indium 115 | 50 Sn tin 119 | 51 Sb antimony 122 | 52 Te tellurium 128 | 53 I iodine 127 | 54 Xe xenon 131 |
55 Cs caesium 133 | 56 Ba barium 137 | 57–71 lanthanoids
| 72 Hf hafnium 178 | 73 Ta tantalum 181 | 74 W tungsten 184 | 75 Re rhenium 186 | 76 Os osmium 190 | 77 Ir iridium 192 | 78 Pt platinum 195 | 79 Au gold 197 | 80 Hg mercury 201 | 81 Tl thallium 204 | 82 Pb lead 207 | 83 Bi bismuth 209 | 84 Po polonium – | 85 At astatine – | 86 Rn radon – |
87 Fr francium – | 88 Ra radium – | 89–103 actinoids
| 104 Rf rutherfordium – | 105 Db dubnium – | 106 Sg seaborgium – | 107 Bh bohrium – | 108 Hs hassium – | 109 Mt meitnerium – | 110 Ds darmstadtium – | 111 Rg roentgenium – | 112 Cn copernicium – | 113 Nh nihonium – | 114 Fl flerovium – | 115 Mc moscovium – | 116 Lv livermorium – | 117 Ts tennessine – | 118 Og oganesson – |
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lanthanoids | 57 La lanthanum 139 | 58 Ce cerium 140 | 59 Pr praseodymium 141 | 60 Nd neodymium 144 | 61 Pm promethium – | 62 Sm samarium 150 | 63 Eu europium 152 | 64 Gd gadolinium 157 | 65 Tb terbium 159 | 66 Dy dysprosium 163 | 67 Ho holmium 165 | 68 Er erbium 167 | 69 Tm thulium 169 | 70 Yb ytterbium 173 | 71 Lu lutetium 175 |
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actinoids | 89 Ac actinium – | 90 Th thorium 232 | 91 Pa protactinium 231 | 92 U uranium 238 | 93 Np neptunium – | 94 Pu plutonium – | 95 Am americium – | 96 Cm curium – | 97 Bk berkelium – | 98 Cf californium – | 99 Es einsteinium – | 100 Fm fermium – | 101 Md mendelevium – | 102 No nobelium – | 103 Lr lawrencium – |
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The volume of one mole of any gas is 24 dm3 at room temperature and pressure (r.t.p.).
The Avogadro constant, L = 6.02 × 1023 mol-1