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Practice paper written from an analysis of every
O-Level Science (Chemistry) paper, 2010–2026
Paper 1 Multiple Choice (Chemistry section)
FORECAST PAPER · SET 10 Hard
For practice before the 2026 examination
30 minutes
Additional Materials: Paper for your answers, numbered 1 to 20
Write in soft pencil.
Do not use staples, paper clips, glue or correction fluid.
There are twenty questions on this paper. Answer all questions. For each question there are four possible answers A, B, C and D.
Choose the one you consider correct and record your choice on a separate sheet of paper, numbered 1 to 20.
Each correct answer will score one mark. A mark will not be deducted for a wrong answer.
Any rough working should be done in this booklet.
A copy of the Data Sheet is printed on page 9.
A copy of the Periodic Table is printed on page 10.
The use of an approved scientific calculator is expected, where appropriate.
A research chemist has a dry mixture of four solids, P, Q, R and S. P dissolves in water but not in propanone. Q dissolves in propanone but not in water. R dissolves in both water and propanone. S dissolves in neither water nor propanone.
The chemist adds propanone to the mixture and filters. Water is added to the residue and the mixture is filtered again. Each filtrate is evaporated to dryness and the final residue is washed and dried.
Which solids are obtained pure?
Ammonium ions, NH4+, are detected in a sample of rain water by a research team.
Each ion contains one nitrogen atom, 147N, and four hydrogen atoms, 11H.
Which row gives the numbers of protons, neutrons and electrons in one ammonium ion?
| protons | neutrons | electrons | |
|---|---|---|---|
| A | 10 | 7 | 10 |
| B | 11 | 7 | 10 |
| C | 11 | 7 | 11 |
| D | 11 | 11 | 10 |
In each diagram, only the outer shell electrons are shown. A dot (•) is an electron from a hydrogen atom and a cross (×) is an electron from the oxygen atom.
Which diagram shows a molecule of water?
Nitrogen trifluoride, NF3, is a gas used to clean the chambers in which computer chips are made.
In a molecule of NF3, the nitrogen atom is joined to each of the three fluorine atoms, and every atom has a noble gas electronic configuration.
How many outer shell electrons in one molecule are not involved in bonding?
Element X is a grey powder that is attracted to a magnet. Element Y is a yellow powder that is not attracted to a magnet. When X and Y are heated together they react to form a black compound, Z, in which one atom of X is joined to one atom of Y. Z is not attracted to a magnet.
A mixture of 5.6 g of X and 4.8 g of Y is sealed in a tube, heated until no more reaction happens and then cooled. The letters are not chemical symbols.
Which statements about the solid in the tube at the end are correct?
A research team studies three ionic compounds.
The ions in the compounds are Al3+, Mg2+, NH4+, N3−, NO3− and SO42−.
Which row gives the formulae of aluminium nitrate, ammonium sulfate and magnesium nitride?
| aluminium nitrate | ammonium sulfate | magnesium nitride | |
|---|---|---|---|
| A | Al(NO3)3 | (NH4)2SO4 | Mg3N2 |
| B | Al(NO3)3 | (NH4)2SO4 | Mg2N3 |
| C | Al(NO3)3 | NH4SO4 | Mg3N2 |
| D | AlNO3 | (NH4)2SO4 | Mg3N2 |
A technician dissolves 0.050 mol of a solid in water and makes the solution up to 250 cm3.
What is the concentration of the solution, in mol / dm3?
Most of the crops on a research farm grow best in soil of pH 6.5 to 7.5. The soil in one plot has a pH of 4.5, so calcium hydroxide is spread on it.
The graph shows how the pH of this soil changes with the mass of calcium hydroxide added to each square metre.
The plot has an area of 10 m2. What mass of calcium hydroxide should be spread on the plot?
The labels have come off three gas cylinders, X, Y and Z. They contain ammonia, carbon dioxide and chlorine, one gas in each.
Damp blue litmus paper is put into gas from X, and it turns red and then white. Damp red litmus paper is put into gas from Z, and it turns blue.
Which row identifies the gases?
| X | Y | Z | |
|---|---|---|---|
| A | ammonia | carbon dioxide | chlorine |
| B | carbon dioxide | ammonia | chlorine |
| C | chlorine | carbon dioxide | ammonia |
| D | chlorine | ammonia | carbon dioxide |
Four elements, W, X, Y and Z, have proton numbers of 2, 3, 10 and 11. The letters are not the chemical symbols.
Which statement is correct?
In Group 17, chlorine is a pale green gas, bromine is a red-brown liquid and iodine is a grey-black solid. Chlorine displaces bromine from aqueous potassium bromide, and bromine displaces iodine from aqueous potassium iodide.
Element Q has a proton number of 85. The letter Q is not the chemical symbol. Use the Periodic Table to predict the properties of Q.
Which row is correct?
| colour of Q | formula of the compound of sodium and Q | reaction of Q with aqueous potassium iodide | |
|---|---|---|---|
| A | dark | Na2Q | no reaction |
| B | dark | NaQ | displaces iodine |
| C | pale | NaQ | no reaction |
| D | dark | NaQ | no reaction |
A research team stores chlorine and argon in separate cylinders. Chlorine gas consists of Cl2 molecules, but argon gas consists of single atoms.
Which statement explains why argon atoms do not join together?
In three experiments, a different change is made to speed up a reaction. In experiment 1, a solid reactant is crushed into a powder. In experiment 2, the pressure on a mixture of reacting gases is increased. In experiment 3, a reaction mixture is heated to a higher temperature.
Which row gives the reason for the faster reaction in each experiment?
| experiment 1: powder | experiment 2: higher pressure | experiment 3: higher temperature | |
|---|---|---|---|
| A | the particles move faster, so they collide more often | the gas particles are closer together, so they collide more often | the particles move faster, so they collide more often |
| B | more of the solid particles are exposed to the other reactant, so they collide more often | the particles move faster, so they collide more often | the particles move faster, so they collide more often |
| C | more of the solid particles are exposed to the other reactant, so they collide more often | the gas particles are closer together, so they collide more often | the gas particles are closer together, so they collide more often |
| D | more of the solid particles are exposed to the other reactant, so they collide more often | the gas particles are closer together, so they collide more often | the particles move faster, so they collide more often |
A research group compares four fuels. For the same amount of energy, the table shows the carbon dioxide given out when each fuel burns and the carbon dioxide taken in from the air by the plants (if any) used to make it.
| fuel | made from | CO2 given out on burning / units | CO2 taken in during growth / units |
|---|---|---|---|
| W | petrol (from crude oil) | 31 | 0 |
| X | ethanol from wheat | 19 | 14 |
| Y | ethanol from maize | 24 | 22 |
| Z | ethanol from sugarcane | 22 | 21 |
Which fuel adds the least carbon dioxide to the atmosphere overall?
Four hydrocarbons, P, Q, R and S, are made by cracking in a research laboratory. Each is an alkane or an alkene. Their relative molecular masses are measured.
| hydrocarbon | relative molecular mass |
|---|---|
| P | 42 |
| Q | 30 |
| R | 56 |
| S | 58 |
Each hydrocarbon is shaken with aqueous bromine. Which two hydrocarbons turn the aqueous bromine from orange to colourless?
A research team measures the carbon dioxide made when ethanol burns completely in air. They burn 2.3 g of ethanol, C2H5OH.
What is the volume of carbon dioxide formed, measured at room temperature and pressure?
Ethene is heated under high pressure in a reactor and is changed into poly(ethene).
Which statements about this change are correct?
Part of the polymer chain in a plastic used to make filter membranes is shown.
The polymer is made by addition polymerisation. Which monomer is used?
Four gas cylinders, W, X, Y and Z, each contain one pure gas. The results of some tests are shown.
Which gas is an atmospheric pollutant?
Scientists measure a rise in the amounts of carbon dioxide and methane in the atmosphere.
Which is a predicted effect of this rise?
| 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