2 Helium, neon, argon, krypton, xenon and radon are noble gases in Group VIII. (a) Name the noble gas which has the greatest volume composition in air. … [1] (b) State one use for helium. … [1] (c) Radon is very unreactive. Use the electronic structure of radon to explain why. … … [1] (d) Two isotopes of radon are shown. 220 86Rn 222 86Rn (i) Give one similarity in the atomic structure of these two isotopes. … [1] (ii) Give one difference in the atomic structure of these two isotopes. … [1] (e) Xenon forms a compound that contains only xenon, oxygen and fluorine. The compound contains 22.1% oxygen by mass and 17.5% fluorine by mass. Calculate the empirical formula of this compound. empirical formula … [3] (f) A sample of neon has a volume of 21 dm3 at room temperature and pressure. (i) The temperature of the sample is increased. The pressure remains constant. Describe and explain, using kinetic particle theory, what happens to the volume of the sample. … … [1] (ii) The pressure of the sample is increased. The temperature remains constant. Describe and explain, using kinetic particle theory, what happens to the volume of the sample. … … [1] (iii) Calculate the mass of neon in the 21 dm3 sample. Give your answer to two significant figures. mass … g [2] [Total: 12]

2(a) argon 1 2(b) (air) balloons / undersea breathing apparatus 1 2(c) outer shell has 8 electrons 1 2(d)(i) 86 protons / 86 electrons / same electronic structure 1 2(d)(ii) radon-222 has two more neutrons / radon-220 has two fewer neutrons / radon-220 has 134 neutrons and radon-222 has 136 neutrons 1 2(e) percentage of xenon = 60.4 (1) mole ratio Xe : O : F is 60.4 / 130 : 22.1 / 16 : 17.5 / 19 OR 0.46 : 1.38 : 0.92 (1) empirical formula XeO3F2 (1) 3 2(f)(i) volume increases AND particles move faster / particles spread out more / particles move further apart 1 2(f)(ii) volume decreases AND particles move closer together / distance between particles decreases 1 2(f)(iii) moles = 21 / 24 OR 0.875 (1) mass = 18 (g) (1) 2 To earn marks, you must correctly name argon, state a valid use for helium, explain radon's unreactivity by mentioning its full outer electron shell, identify a similarity (protons/electrons/electronic structure) and a difference (number of neutrons) between the isotopes, and correctly calculate the empirical formula by showing the percentage of xenon, the mole ratios, and the final formula. For parts (f)(i) and (f)(ii), you need to state the change in volume and explain it in terms of particle movement. For (f)(iii), you must correctly calculate the moles and then the mass.

2 Oxygen, sulfur, selenium, tellurium and polonium are in Group VI. (a) State the percentage composition by volume of oxygen in dry air. … [1] (b) State one large-scale use for oxygen. … [1] (c) Two isotopes of polonium are shown. 20 8 9 4Po 21 8 0 4Po (i) Explain why both isotopes have the same chemical properties. … [1] (ii) Give one difference in the atomic structure of these two isotopes. … [1] (d) Selenium forms a compound that contains only selenium, oxygen and chlorine. The compound contains 9.6% oxygen by mass and 42.8% chlorine by mass. Calculate the empirical formula of this compound. empirical formula … [3] (e) A sample of oxygen has a volume of 11.5 dm3 at room temperature and pressure. (i) The temperature of the sample is decreased. The pressure remains constant. Describe and explain, using kinetic particle theory, what happens to the volume of the sample. … … [1] (ii) The pressure of the sample is decreased. The temperature remains constant. Describe and explain, using kinetic particle theory, what happens to the volume of the sample. … … [1] (iii) Calculate the mass of oxygen in the 11.5 dm3 sample at room temperature and pressure. Give your answer to two significant figures. mass … g [2] [Total: 11]

2(a) 21 (%) 1 2(b) steel making / welding / cutting metals / oxygen tents in hospitals / breathing apparatus / fuel cells 1 2(c)(i) same electronic structure / same electronic configuration 1 2(c)(ii) polonium-210 has one more neutron / polonium-209 has one less neutron / polonium-209 has 125 neutrons and polonium- 210 has 126 neutrons 1 2(d) percentage of selenium = 47.6 (1) mole ratio Se : O : Cl is 47.6 / 79 : 9.6 / 16 : 42.8 / 35.5 OR 0.60 : 0.60 : 1.21 (1) empirical formula SeOCl 2 (1) 3 2(e)(i) volume decreases AND particles move slower / particles less spread out / particles closer together 1 2(e)(ii) volume increases AND particles move further apart / particles more spread out / distance between particles increases 1 2(e)(iii) mol = 11.5 / 24 OR 0.479(117) (1) mass = 15 (g) (1) 2 To earn marks, you must provide the correct percentage for oxygen in air, state a valid large-scale use for oxygen, explain that isotopes have the same chemical properties due to identical electronic structures, and identify the difference in neutron count between the given isotopes. For the empirical formula calculation, you need to correctly calculate the percentage of selenium, determine the mole ratios, and then state the correct empirical formula. For part (e)(i), you must state that the volume decreases and explain this using kinetic particle theory by mentioning particles moving slower or being closer together. For part (e)(ii), you must state that the volume increases and explain this by mentioning particles moving further apart or being more spread out. For part (e)(iii), you must correctly calculate the moles of oxygen and then use this to find the mass.

3 (a) A drop of black ink is placed at the bottom of a beaker of water. After a time, the colour of the ink spreads throughout the water. Explain this observation in terms of the kinetic particle theory. … … … … … [3] (b) In the past, ink was made from a mixture containing iron(II) ions and tannic acid. (i) Describe a test for iron(II) ions. test … observations … [2] (ii) The ink darkens when used on paper. This is because iron(II) ions are oxidised to iron(III) ions. Write the ionic equation for this reaction. … [1] (iii) After a time, the ink fades because of a hydrolysis reaction which is catalysed by acids. State how a catalyst increases the rate of a chemical reaction. … … [1] (c) Paper is made of cellulose. Cellulose is a complex carbohydrate (polysaccharide). (i) Name one other complex carbohydrate (polysaccharide). … [1] (ii) Describe how complex carbohydrates can be hydrolysed to simple sugars. … … [2] [Total: 10]

3(a) any three from: • diffusion • particles move (from place to place) / particles collide • random (movement) of particles / particles go anywhere / particles (move) in all directions / particles disperse • intermingling of particles / mixing of particle • (bulk movement of ink particles) from higher to lower concentration 3 3(b)(i) (aqueous) sodium hydroxide / (aqueous) ammonia (1) (light) green precipitate (1) 2 3(b)(ii) Fe2+ → Fe3+ + e– 1 3(b)(iii) lowers the activation energy 1 3(c)(i) starch 1 3(c)(ii) reflux / heat / boil (1) with (concentrated) hydrochloric acid (1) 2 (a) To earn marks, you need to mention diffusion, particle movement/collisions, random movement/dispersal, intermingling/mixing of particles, and movement from higher to lower concentration. (b)(i) To earn the first mark, you must state the reagent as aqueous sodium hydroxide or aqueous ammonia. To earn the second mark, you must state the observation as a light green precipitate. (b)(ii) To earn the mark, you must write the ionic equation as Fe2+ → Fe3+ + e–. (b)(iii) To earn the mark, you must state that the catalyst lowers the activation energy. (c)(i) To earn the mark, you must identify 'starch' as the indicator. (c)(ii) To earn the first mark, you must state 'reflux', 'heat', or 'boil'. To earn the second mark, you must specify 'with (concentrated) hydrochloric acid'.

4 This question is about halogens and halogen compounds. (a) A drop of bromine liquid was placed in a sealed glass jar. After a time, the colour of the bromine had spread throughout the jar. Explain this observation in terms of the kinetic particle theory. … … … … … [3] (b) Chlorine, bromine and iodine are halogens. (i) State the trend in the colour of the halogens from chlorine to iodine. … … [1] (ii) State the physical state of chlorine and iodine at room temperature and pressure. chlorine … iodine … [1] (iii) Chlorine is used to make other chemicals. State one other use of chlorine. … [1] (c) The molecular structure of a compound of iodine and chlorine is shown. Cl Cl I Cl Cl Cl Cl I Deduce the molecular formula of this compound. … [1] (d) Fluorine reacts with aqueous sodium hydroxide to produce sodium fluoride, NaF, water and oxygen. 2F2 + 4NaOH 4NaF + 2H2O + O2 Calculate the maximum volume of oxygen produced, in dm3, at room temperature and pressure, when 0.037 mol of sodium hydroxide react completely with fluorine. Give your answer to two significant figures. volume of oxygen … dm3 [2] [Total: 9]

4(a) any three from: • evaporation • particles with highest kinetic energy escape the liquid / particle moving the fastest escape the liquid • diffusion • particles move (from place to place) / particles collide • random (movement) of particles / particles go anywhere / particles (move) in all directions / particles disperse • intermingling of particles / mixing of particles • (bulk movement of bromine particles) from higher to lower concentration 3 4(b)(i) darker / lighter up the Group 1 4(b)(ii) chlorine gas and iodine solid 1 4(b)(iii) disinfectant / killing bacteria / bleach 1 4(c) I2Cl6 1 4(d) mol oxygen = 0.037 4 OR 9.25 × 10–3 (1) volume of oxygen = 0.22 (dm3) (1) 2

Cambridge O Level Chemistry · 5070

O-Level Chemistry (5070) States of matter past paper questions

Revise O-Level Chemistry (5070) — States of matter with real Cambridge past-paper questions grouped by topic, each shown with its marking scheme. Working one topic at a time targets exactly the skill each question tests.

50 free questions from 2016–2021, each with its marking scheme. Open the full topical bank to filter by subtopic, paper, and year.

States of matter in O-Level Chemistry 5070 exams, 2020–2025

Across 2020–2025, States of matter accounted for 61 questions worth 312 marks in Cambridge O Level Chemistry (5070) papers.

By year
Year	Questions	Marks
2020	10	54
2021	5	26
2022	10	31
2023	12	58
2024	10	65
2025	14	78

Most-tested subtopics

1.1 Solids, liquids and gases245 marks
1.2 Diffusion53 marks

Appears in

Paper 1 · 32 qs
Paper 2 · 25 qs
Paper 4 · 4 qs

All most-tested Chemistry topics

2021 May/Jun · Paper 2 · Q2 · 12 marks
Marking scheme
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2021 May/Jun · Paper 2 · Q2 · 11 marks
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2020 Oct/Nov · Paper 2 · Q3 · 10 marks
Marking scheme
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2020 Oct/Nov · Paper 2 · Q4 · 9 marks
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2021 May/Jun · Paper 1 · Q6 · 1 mark
Marking scheme
Mark scheme — 2021 Paper 1 Q6
Answer: A
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