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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 3.1
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.
Different techniques are used to separate mixtures and to check the purity of substances.
Choose from the techniques listed to answer the questions.
Each technique can be used once, more than once or not at all.
Identify the technique which:
separates a mixture of two liquids that mix completely and have different boiling points, such as ethanol and water
separates the coloured dyes in a sample of ink
uses a temperature reading to show that a sample of a solid is pure.
Table 2.1 shows information about four particles, W, X, Y and Z. The letters are not the chemical symbols.
| particle | charge | nucleon number | number of protons | number of neutrons | number of electrons |
|---|---|---|---|---|---|
| W | 0 | 23 | 11 | 11 | |
| X | 0 | 22 | 11 | 11 | 11 |
| Y | 2+ | 24 | 12 | 12 | |
| Z | 1− | 19 | 9 | 10 | 10 |
Complete Table 2.1.
Particles W and X are isotopes of the same element.
Define the term isotopes.
Table 3.1 shows some properties of three substances, K, L and M. The letters are not the chemical symbols.
| substance | melting point / °C | conducts electricity when solid | conducts electricity when molten |
|---|---|---|---|
| K | 805 | no | yes |
| L | 56 | no | no |
| M | 1240 | yes | yes |
Use data from Table 3.1 to deduce which substance is a metal. Give a reason for your answer.
Substance K is an ionic compound.
Explain why K conducts electricity when molten but not when solid.
Use ideas about ions in your answer.
Substance L has a simple molecular structure.
Explain why L has a low melting point.
Use ideas about structure and bonding in your answer.
Metals such as M are often made into alloys.
Describe what is meant by the term alloy.
Most crops grow best in soil that has a pH close to 7.
The water in a sample of soil has a pH of 4.5.
State the name or the formula of the ion that is present in a higher concentration in this soil water than in pure water.
A farmer adds calcium hydroxide to the soil.
Explain why this increases the pH of the soil.
Write the ionic equation, including state symbols, for the neutralisation reaction that takes place.
Ammonium sulfate is a fertiliser that provides nitrogen for plants.
A farmer should not add calcium hydroxide and ammonium sulfate to the soil at the same time.
Explain why.
Magnesium reacts with dilute sulfuric acid to form hydrogen.
In experiment 1, an excess of dilute sulfuric acid at 25 °C is added to 0.12 g of magnesium ribbon. The hydrogen is collected in a 250 cm3 gas syringe.
Experiment 1 is repeated at an increased temperature of 35 °C. This is experiment 2. All other conditions are kept the same. Fig. 5.1 shows how the volume of hydrogen collected changes with time in each experiment.
State the time taken for 80 cm3 of hydrogen to be collected in experiment 2.
Explain why the rate of reaction is higher in experiment 2. Use ideas about particles in your answer.
The final volume of hydrogen is the same in both experiments. Explain why.
A thermometer in the mixture in experiment 1 shows a rise in temperature.
State what this shows about the energy change in the reaction.
Some cars burn a fuel that is a mixture of petrol and bioethanol. The bioethanol is made from the sugar in sugar cane.
Carbon monoxide is a pollutant that can form when petrol burns in a car engine.
State why carbon monoxide, instead of carbon dioxide, is formed.
State one harmful effect of carbon monoxide on people.
State one source of carbon dioxide in the atmosphere other than the burning of fuels.
State why bioethanol is described as a renewable fuel.
Explain why burning bioethanol causes a smaller increase in the amount of carbon dioxide in the atmosphere than burning petrol.
Use ideas about photosynthesis in your answer.
Fig. 7.1 describes the reaction of solid R with an excess of acid S to form three products, T, U and X.
It also shows some of the reactions of solution T.
Identify each of R, S, T, U, V, W and X.
You may give the name or the formula of each.
Write a balanced chemical equation, including state symbols, for any one of the reactions shown in Fig. 7.1.
Lithium hydroxide, LiOH, removes carbon dioxide from the air in spacecraft.
Define the term relative atomic mass.
Calculate the relative formula mass, Mr, of lithium hydroxide.
A canister contains 240 g of lithium hydroxide.
Calculate the amount, in moles, of lithium hydroxide in the canister.
Use your answer to (c) and the equation to calculate the volume of carbon dioxide, at room temperature and pressure, that reacts.
A student dissolves 0.20 mol of lithium hydroxide in water to make 200 cm3 of solution.
Calculate the concentration of the solution in mol / dm3.
Alkenes are hydrocarbons. Table 9.1 shows some members of the alkene series.
| name | number of carbon atoms | molecular formula |
|---|---|---|
| ethene | 2 | C2H4 |
| propene | 3 | |
| an alkene with 4 carbon atoms | 4 | C4H8 |
| an alkene with 6 carbon atoms | 6 |
Complete Table 9.1.
State the general formula of the alkenes.
Alkenes form a homologous series.
State one characteristic of a homologous series, other than having the same general formula.
Draw the displayed formula of propene.
Show all the atoms and all the bonds.
Propane and propene are both colourless gases.
Describe a test, using aqueous bromine, that shows which gas is propene.
Include the result for each gas.
Propene forms the polymer poly(propene) by addition polymerisation.
Draw a section of the structure of poly(propene) that shows two repeat units.
You may write the methyl group as CH3.
Propene reacts with hydrogen to form propane.
Write a balanced chemical equation for this reaction.
Metals can be arranged in order of their reactivity.
A student adds equal-sized pieces of four metals, W, X, Y and Z, to separate samples of dilute hydrochloric acid. The concentration and temperature of the acid are the same in each experiment. The letters are not the chemical symbols.
| metal | observations |
|---|---|
| W | many bubbles produced quickly; the metal dissolves |
| X | no bubbles produced |
| Y | extremely vigorous reaction with very many bubbles; the test-tube becomes hot |
| Z | a few bubbles produced slowly |
Use data from Table 10.1 to deduce the order of reactivity of the four metals. Start with the most reactive.
The four metals are calcium, copper, magnesium and zinc. Identify metal W.
Iron rusts when it is in contact with certain substances.
State the two substances needed for iron to rust.
Fig. 10.1 shows five iron nails set up in test-tubes at the start of an experiment. Boiled water contains no dissolved air. The drying agent absorbs water vapour from the air. Sodium chloride speeds up the rusting of iron. Identify the tube in which the nail rusts first.
The iron railings of a school are painted. Explain how painting stops the iron from rusting.
Copper can be obtained from its ore by heating the ore with carbon. Explain why it is much more difficult to obtain calcium than copper from its ore.
Magnesium reacts with oxygen to form magnesium oxide, an ionic compound. Draw a 'dot-and-cross' diagram to show the bonding in magnesium oxide. Show only the outer shell electrons. Include the charge on each ion.
The equation for the reaction is shown.
Chlorine, bromine and iodine are halogens in Group 17.
A student adds an aqueous solution of one halogen to an aqueous solution of a potassium halide. The volumes and concentrations of the solutions are the same in each experiment. Table 11.1 shows the observations.
| experiment | aqueous halogen added | aqueous potassium halide | observations |
|---|---|---|---|
| 1 | chlorine | potassium bromide | the solution turns orange |
| 2 | chlorine | potassium iodide | the solution turns brown |
| 3 | bromine | potassium chloride | no change |
| 4 | bromine | potassium iodide | the solution turns brown |
| 5 | iodine | potassium bromide | no change |
Use data from Table 11.1 to deduce the order of reactivity of the three halogens. Start with the most reactive.
Complete the word equation for experiment 1.
Fluorine, F, has proton number 9. Chlorine, Cl, has proton number 17. Explain why fluorine and chlorine are in the same group of the Periodic Table. Answer in terms of electronic configuration.
Name the product that makes the solution orange in experiment 1 of Table 11.1.
Predict whether iodine reacts with aqueous potassium chloride. Use Table 11.1 to explain your answer.
Hydrogen chloride, HCl, is formed when hydrogen reacts with chlorine. Hydrogen chloride is a covalent compound. Draw a 'dot-and-cross' diagram to show the bonding in a molecule of hydrogen chloride. Show only the outer shell electrons.
The equation for the reaction in experiment 1 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