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Practice paper written from an analysis of every
O-Level Chemistry paper, 2009–2025
Paper 2
FORECAST PAPER
For practice before the 2026 examination
1 hour 45 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 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 80.
Table 1.1 shows some properties of four substances, P, Q, R and S. The letters are not the chemical symbols.
| substance | melting point / °C | conducts electricity as a solid | conducts electricity as a liquid |
|---|---|---|---|
| P | 770 | no | yes |
| Q | 53 | no | no |
| R | 1710 | no | no |
| S | 1085 | yes | yes |
Use the data in Table 1.1 to complete Table 1.2.
Choose from: giant covalent, ionic, metallic, simple molecular.
Each structure can be used once, more than once or not at all.
| substance | type of structure |
|---|---|
| P | |
| Q | |
| R | |
| S |
Substance Q has a simple molecular structure.
Explain why Q does not conduct electricity as a liquid.
Substance R is silicon(IV) oxide, SiO2. Carbon dioxide, CO2, also contains covalent bonds but is a gas at room temperature.
Explain why silicon(IV) oxide has a much higher melting point than carbon dioxide.
Use ideas about structure and bonding in your answer.
Metals such as S can be mixed with other elements to make alloys.
Fig. 1.1 shows the arrangement of atoms in a pure metal and in an alloy of that metal.
State which diagram, 1 or 2, shows the alloy.
Explain why an alloy is harder than the pure metal.
Table 2.1 shows four particles written in nuclide notation.
| particle | number of protons | number of neutrons | number of electrons |
|---|---|---|---|
| 64 30Zn | 30 | 30 | |
| 66 30Zn2+ | 30 | 36 | |
| 80 35Br− | 35 | 45 | |
| 84 36Kr | 36 | 36 |
Complete Table 2.1.
Identify the two particles in Table 2.1 that have the same number of electrons.
Give the symbol of each particle.
Dichlorine monoxide, Cl2O, is a covalent compound. Each molecule contains one oxygen atom bonded to two chlorine atoms.
State what is meant by a covalent bond.
Draw a 'dot-and-cross' diagram to show the bonding in a molecule of dichlorine monoxide.
Show the outer shell electrons only.
A student uses paper chromatography on a sample of a green food colouring. The chromatogram has two coloured spots.
State what this shows about the green food colouring.
Tungsten is a metal used in the filaments of lamps. It is made by heating solid tungsten(VI) oxide, WO3, in a stream of hydrogen gas. The products are solid tungsten and steam.
Write a balanced chemical equation, including state symbols, for this reaction.
Calculate the relative formula mass, Mr, of tungsten(VI) oxide, WO3.
A furnace is loaded with 69.6 g of tungsten(VI) oxide. The furnace is supplied with 14.4 dm3 of hydrogen, measured at room temperature and pressure.
Use the equation in (a) to show, by calculation, that hydrogen is the limiting reactant.
Calculate the maximum mass of tungsten that can be made in the furnace.
The furnace produces 33.12 g of tungsten.
Calculate the percentage yield of tungsten.
Potassium nitrate is a soluble salt that is used in fertilisers.
Table 4.1 shows the pH of solutions of nitric acid and ethanoic acid.
| acid | concentration / mol / dm3 | pH |
|---|---|---|
| nitric acid | 0.010 | 2.0 |
| ethanoic acid | 0.20 | 2.7 |
Identify the stronger acid and explain your answer.
Potassium nitrate crystals are made from aqueous potassium hydroxide and dilute nitric acid.
Explain why excess solid potassium hydroxide cannot be used and then filtered off.
Describe how you would make pure, dry crystals of potassium nitrate from the two solutions.
Barium sulfate is insoluble in water.
Name two aqueous solutions that could be mixed to make a precipitate of barium sulfate.
In a titration, 25.0 cm3 of aqueous potassium hydroxide is exactly neutralised by 20.0 cm3 of dilute sulfuric acid of concentration 0.0500 mol / dm3.
Calculate the concentration of the potassium hydroxide in mol / dm3.
Chloroethene, CH2=CHCl, is the monomer used to make the plastic poly(chloroethene). Chloroethene is made from ethene, which is produced by cracking alkanes.
Nonane, C9H20, is cracked to form heptane, C7H16, and an alkene, X.
Deduce the molecular formula of X.
Ethene reacts with bromine to form 1,2-dibromoethane, C2H4Br2.
Name the type of reaction that takes place.
Draw the displayed formula of 1,2-dibromoethane.
Explain, in terms of its structure, why ethene is described as an unsaturated hydrocarbon.
Chloroethene forms the polymer poly(chloroethene) by addition polymerisation.
Draw the structure of poly(chloroethene) to show two repeat units.
Part of the structure of the polymer poly(tetrafluoroethene) is shown below.
Draw the displayed formula of the monomer used to make this polymer.
Butane, C4H10, has an isomer with a branched chain.
Draw the displayed formula of this isomer.
Marble chips, CaCO3, react with dilute hydrochloric acid.
In experiment 1, an excess of marble chips is added to 50 cm3 of 1.0 mol / dm3 hydrochloric acid in a conical flask at 25 °C. The flask is placed on a balance. Cotton wool in the neck of the flask lets the gas escape but stops liquid spraying out.
Experiment 2 is the same as experiment 1, except that the acid is at 40 °C.
Table 6.1 shows the mass of the flask and its contents during each experiment.
| time / s | 0 | 20 | 40 | 60 | 80 | 100 |
|---|---|---|---|---|---|---|
| mass of flask and contents in experiment 1 / g | 155.00 | 154.70 | 154.48 | 154.32 | 154.20 | 154.12 |
| mass of flask and contents in experiment 2 / g | 155.00 | 154.46 | 154.19 | 154.05 | 153.98 | 153.94 |
Fig. 6.1 shows the energy profile diagram for the reaction.
State whether the reaction is exothermic or endothermic. Give a reason for your answer.
On Fig. 6.1, draw and label:
A catalyst increases the rate of some reactions.
On Fig. 6.1, draw the energy profile for this reaction if a catalyst were used. Label this curve C.
Explain, in terms of the energy changes when bonds break and form, why the reaction is exothermic.
Explain the effect of the higher temperature on the rate of reaction. Use ideas about particles in your answer.
Use data from Table 6.1 to calculate the volume of carbon dioxide, at room temperature and pressure, that has escaped from the flask in experiment 1 in the first 100 s. Give your answer in cm3.
Aluminium reacts vigorously with iodine, a Group 17 element. A few drops of water start the reaction between aluminium powder and iodine. Heat is given out and a purple vapour forms.
Deduce the oxidation states of aluminium and iodine in aluminium iodide, AlI3.
Identify the oxidising agent in this reaction. Explain your answer in terms of electron transfer.
Calculate the relative formula mass of aluminium iodide, AlI3.
Dilute nitric acid, followed by aqueous silver nitrate, is added to aqueous aluminium iodide.
State what you would see.
Aluminium also reacts with oxygen in the air.
Aluminium has proton number 13. It is in Period 3 of the Periodic Table.
Write the electronic configuration of an aluminium atom and state its group number.
Explain, in terms of outer electrons, why aluminium forms a 3+ ion.
Describe how the character of the elements changes from left to right across Period 3, from sodium to chlorine.
Natural gas, which is mainly methane, and crude oil are both used as fuels.
Crude oil is a mixture of hydrocarbons. It is separated into fractions by fractional distillation.
State the property of the hydrocarbon molecules that allows them to be separated by fractional distillation.
A gas cooker burns 3.2 g of methane completely in excess oxygen. The equation for the reaction is shown.
Nitrogen oxides are air pollutants that form inside car engines. Describe how they form.
Nitrogen dioxide dissolves in rain water to form acid rain.
State one effect of acid rain on buildings.
Catalytic converters in cars also remove unburnt hydrocarbons from the exhaust gases. Ethene, C2H4, reacts with oxygen to form carbon dioxide and water.
Write a balanced chemical equation for this reaction.
Propan-1-ol is an alcohol with three carbon atoms in an unbranched chain.
Draw the displayed formula of propan-1-ol.
Ethanoic acid is a weak acid. It reacts with magnesium.
Name the two products of this reaction.
Esters are made from carboxylic acids and alcohols. The structure of an ester is shown below.
Name the carboxylic acid and the alcohol that react to form this ester.
Dilute sulfuric acid is electrolysed using graphite electrodes, as shown in Fig. 9.1.
The graphite electrodes do not react. The solution contains H+ and SO42− ions, and water molecules.
Explain why aqueous sulfuric acid conducts electricity.
Name the product formed at the cathode and the product formed at the anode.
Write the ionic half-equation for the reaction at the anode.
The half-equation for the reaction at the cathode is 2H+(aq) + 2e− → H2(g). Explain why this reaction is reduction.
A student adds a piece of one metal to an aqueous solution of the nitrate of another metal. Table 9.1 shows the observations.
| experiment | metal added | aqueous solution | observations |
|---|---|---|---|
| 1 | magnesium | copper(II) nitrate | pink-brown solid forms on the magnesium; blue solution fades |
| 2 | copper | silver nitrate | silvery crystals form on the copper; solution turns blue |
| 3 | silver | copper(II) nitrate | no change |
| 4 | copper | magnesium nitrate | no change |
Use data from Table 9.1 to deduce the order of reactivity of magnesium, copper and silver. Start with the most reactive. Explain your answer.
Write the ionic equation, including state symbols, for the reaction in experiment 2.
Table 9.2 shows what happens when two metal oxides are each heated strongly with carbon.
| oxide heated with carbon | observations |
|---|---|
| copper(II) oxide | the black solid turns pink-brown |
| magnesium oxide | no change |
Explain why carbon cannot be used to obtain magnesium from magnesium oxide.
Use your answer to (e) to predict whether silver oxide is reduced when it is heated with carbon. Explain your answer.
Molten lead(II) bromide is electrolysed using carbon electrodes in a fume cupboard, as shown in Fig. 10.1.
The carbon electrodes do not react. The molten electrolyte contains Pb2+ and Br− ions.
Explain why solid lead(II) bromide does not conduct electricity but molten lead(II) bromide does.
Name the product formed at the cathode and the product formed at the anode.
Write the ionic half-equation for the reaction at the anode.
The half-equation for the reaction at the cathode is Pb2+(l) + 2e− → Pb(l). Explain why this reaction is reduction.
The alkali metals are in Group 1. Table 10.1 shows the melting points of three Group 1 metals and their observations when added to water.
| Group 1 metal | melting point / °C | observations when added to water |
|---|---|---|
| lithium | 181 | floats; fizzes steadily; does not melt |
| sodium | 98 | floats; melts into a ball; moves quickly; fizzes rapidly |
| potassium | 63 | floats; melts into a ball; moves very quickly; lilac flame |
Rubidium is below potassium in Group 1. Predict the melting point of rubidium and what you would see when a piece of rubidium is added to water.
Lithium reacts with water to form aqueous lithium hydroxide and hydrogen. Write the balanced equation, including state symbols, for this reaction.
Iron is a transition element. Table 10.2 compares iron with potassium, which is not a transition element.
| metal | melting point / °C | density / g / cm3 | colour of aqueous chloride |
|---|---|---|---|
| potassium | 63 | 0.86 | potassium chloride: colourless |
| iron | 1538 | 7.87 | iron(II) chloride: pale green |
Use data from Table 10.2 to state one property of iron typical of a transition element.
Use data from Table 10.2 to state one property of compounds of transition elements.
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