IGCSE Chemistry 0620 Paper 2 Practice Paper (Extended Multiple Choice) — 40 questions, 45 minutes, answers and explanations

Original IGCSE Chemistry 0620 Paper 2 (Extended multiple choice) practice paper: 40 questions, 40 marks, 45 minutes, all twelve syllabus areas, with answers.

Syllabus areas and marks

Questions (40 items, 1 mark each)

1.　At the same temperature and pressure, methane (Mr = 16) diffuses 24 cm in 60 s. How far does sulfur dioxide (Mr = 64) diffuse in the same time?

A　48 cm

B　6.0 cm

C　12 cm

D　3.0 cm

2.　25 g of ice at 0 °C is melted completely. The specific latent heat of fusion of ice is 334 J/g. How much energy is needed?

A　8.35 kJ

B　16.7 kJ

C　334 kJ

D　0.13 kJ

3.　How many neutrons are there in one atom of potassium-39?

A　19

B　20

C　39

D　58

4.　An element has the electron configuration 2, 8, 6. Which group of the Periodic Table does it belong to?

A　Group II

B　Group IV

C　Group VII

D　Group VI

5.　Chlorine has two isotopes: 75% ³⁵Cl and 25% ³⁷Cl. What is the relative atomic mass of chlorine?

A　35.5

B　35.0

C　36.0

D　37.0

6.　The aluminium ion is Al³⁺ and the oxide ion is O²⁻. What is the formula of aluminium oxide?

A　AlO

B　Al₃O₂

C　Al₂O₃

D　AlO₂

7.　Why does graphite conduct electricity while diamond does not?

A　Graphite has a simple molecular structure with weak forces between molecules.

B　Each carbon atom in graphite has one delocalised electron that can move freely within a layer.

C　Graphite contains ions that are free to move.

D　The bonds in graphite are weak, so its melting point is low.

8.　Calcium nitrate has the formula Ca(NO₃)₂. What is its relative molecular mass?

A　56

B　96

C　150

D　164

9.　What percentage by mass of ammonium nitrate, NH₄NO₃, is nitrogen?

A　17.5%

B　21.2%

C　35.0%

D　28.0%

10.　4.8 g of magnesium burns completely in oxygen (2Mg + O₂ → 2MgO). What mass of magnesium oxide is formed?

A　8.0 g

B　4.0 g

C　4.8 g

D　6.4 g

11.　A compound contains 40.0% carbon, 6.7% hydrogen and 53.3% oxygen by mass. What is its empirical formula?

A　CHO

B　CH₂O

C　C₂H₄O

D　C₂H₆O

12.　A current of 2.0 A passes through copper(II) sulfate solution for 965 s. What mass of copper is deposited at the cathode? (Cu²⁺ + 2e⁻ → Cu; 1 mol of electrons = 96 500 C)

A　0.032 g

B　0.32 g

C　1.28 g

D　0.64 g

13.　How much charge is needed to deposit 1.28 g of copper from copper(II) sulfate solution? (1 mol of electrons = 96 500 C)

A　3 860 C

B　1 930 C

C　7 720 C

D　96 500 C

14.　When dilute sulfuric acid is electrolysed with platinum electrodes, what is the volume ratio of the gases at the cathode and the anode (H₂ : O₂)?

A　1 : 1

B　1 : 2

C　2 : 1

D　4 : 1

15.　The bond energies are: H–H 436 kJ/mol, Cl–Cl 243 kJ/mol, H–Cl 431 kJ/mol. What is ΔH for H₂ + Cl₂ → 2HCl?

A　−247 kJ/mol

B　−183 kJ/mol

C　+183 kJ/mol

D　+247 kJ/mol

16.　The enthalpy of combustion of hydrogen is −286 kJ/mol. How much energy is released when 2.0 g of hydrogen burns completely?

A　143 kJ

B　572 kJ

C　71.5 kJ

D　286 kJ

17.　A strip of magnesium is added to dilute hydrochloric acid and 0.60 g of magnesium reacts in 30 s. What is the average rate of reaction?

A　0.020 g/s

B　0.050 g/s

C　18 g/s

D　0.20 g/s

18.　How does a catalyst increase the rate of a reaction without changing the yield?

A　It increases the equilibrium yield.

B　It increases the energy released.

C　It lowers the activation energy so more particles have enough energy to react, and it is not used up.

D　It changes the products formed.

19.　N₂(g) + 3H₂(g) ⇌ 2NH₃(g) is at equilibrium. What happens if the pressure is increased at constant temperature?

A　The equilibrium shifts to the left.

B　There is no change because the reaction is reversible.

C　The equilibrium shifts to the right and the ammonia yield falls.

D　The equilibrium shifts to the right and the ammonia yield rises.

20.　What is the oxidation number of sulfur in sulfuric acid, H₂SO₄?

A　+2

B　+6

C　+4

D　−2

21.　25.0 cm³ of 0.100 mol/dm³ sodium hydroxide solution exactly neutralises 20.0 cm³ of hydrochloric acid. What is the concentration of the acid?

A　0.125 mol/dm³

B　0.0800 mol/dm³

C　0.100 mol/dm³

D　0.200 mol/dm³

22.　Which of these oxides is amphoteric, reacting with both acids and alkalis?

A　Sodium oxide

B　Sulfur dioxide

C　Aluminium oxide

D　Calcium oxide

23.　Which method prepares insoluble barium sulfate?

A　Add barium carbonate to dilute sulfuric acid.

B　Add barium chloride solution to sodium sulfate solution and filter off the precipitate.

C　Titrate barium hydroxide with hydrochloric acid.

D　Heat barium metal in air.

24.　5.0 g of calcium carbonate reacts with excess dilute hydrochloric acid. What volume of carbon dioxide is collected at room temperature and pressure? (1 mol of gas = 24 dm³)

A　0.050 dm³

B　0.60 dm³

C　2.4 dm³

D　1.2 dm³

25.　Going down Group I from lithium to potassium, how does reactivity change and why?

A　It decreases because the atoms get larger.

B　It stays the same for every member.

C　It increases because the outer electron is lost more easily as the atom gets larger.

D　It increases because the atoms gain electrons more easily.

26.　Which of these halogens is the most reactive?

A　Fluorine

B　Chlorine

C　Bromine

D　Iodine

27.　Why are the noble gases (Group VIII) almost unreactive?

A　Their atoms are too large.

B　They exist as diatomic molecules.

C　They have too few electron shells.

D　They have a complete outer shell, so they do not need to gain or lose electrons.

28.　4.0 g of calcium burns completely in oxygen (2Ca + O₂ → 2CaO). What mass of calcium oxide is formed?

A　4.0 g

B　5.6 g

C　8.0 g

D　6.4 g

29.　How is aluminium extracted industrially from its ore, bauxite?

A　Heating aluminium oxide with carbon monoxide.

B　Reacting aluminium with steam.

C　Electrolysis of molten aluminium oxide dissolved in cryolite.

D　Reducing aluminium chloride with hydrogen.

30.　In a blast furnace Fe₂O₃ + 3CO → 2Fe + 3CO₂. What mass of iron is obtained from 320 kg of iron(III) oxide?

A　224 kg

B　112 kg

C　448 kg

D　320 kg

31.　Brass is an alloy of which two metals?

A　Copper and tin

B　Iron and carbon

C　Copper and lead

D　Copper and zinc

32.　Which method protects iron from rusting by sacrificial protection?

A　Coating the iron with oil.

B　Attaching a block of zinc to the iron.

C　Attaching a block of copper to the iron.

D　Keeping the iron in dry air.

33.　What mass of carbon dioxide is formed when 1 mol of methane burns completely?

A　44 g

B　16 g

C　22 g

D　88 g

34.　What environmental problem is caused mainly by burning sulfur-containing coal?

A　Global dimming, because carbon dioxide is formed.

B　Ozone depletion, because nitrogen is formed.

C　Acid rain, because sulfur dioxide is formed.

D　Eutrophication, because hydrogen is formed.

35.　What is the relative molecular mass of pentane, C₅H₁₂?

A　60

B　58

C　70

D　72

36.　0.10 mol of ethene just decolourises bromine water (C₂H₄ + Br₂ → C₂H₄Br₂). What mass of bromine is used?

A　8.0 g

B　16 g

C　32 g

D　160 g

37.　How many structural isomers does butane, C₄H₁₀, have?

A　2

B　3

C　4

D　1

38.　90 g of glucose ferments completely (C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂). What mass of ethanol is formed?

A　23 g

B　92 g

C　46 g

D　180 g

39.　In paper chromatography a spot moves 3.0 cm from the start line while the solvent front moves 8.0 cm. What is its Rf value?

A　3.8

B　0.27

C　2.7

D　0.38

40.　Which method best separates a mixture of ethanol (b.p. 78 °C) and water (b.p. 100 °C)?

A　Filtration

B　Fractional distillation

C　Chromatography

D　Crystallisation

Answers and explanations

Q1　C　Rate of diffusion is proportional to 1/√Mr: √(16 ÷ 64) = ½, so the distance is 24 × ½ = 12 cm. 48 cm reverses the ratio.

Q2　A　E = mL = 25 × 334 = 8 350 J = 8.35 kJ. The temperature stays at 0 °C; the energy only breaks the ice lattice.

Q3　B　Neutrons = mass number − proton number = 39 − 19 = 20. 19 is the proton number and 39 counts protons plus neutrons.

Q4　D　Six electrons in the outer shell means Group VI (proton number 16, sulfur). The group number comes from the outer-shell electrons, not the number of shells.

Q5　A　Ar = 35 × 0.75 + 37 × 0.25 = 26.25 + 9.25 = 35.5. It is a weighted mean, not the midpoint 36 of the two mass numbers.

Q6　C　The charges must balance: 2 × (+3) = +6 and 3 × (−2) = −6, so the formula is Al₂O₃. Al₃O₂ swaps the numbers and leaves +9 − 4, which is not balanced.

Q7　B　Each carbon in a graphite layer bonds with three of its four outer electrons; the fourth is delocalised and can move along the layer, so graphite conducts. In diamond all four electrons are used in bonds, so there are no free electrons.

Q8　D　Mr = 40 + 2 × (14 + 3 × 16) = 40 + 2 × 62 = 40 + 124 = 164. 96 counts only the oxygen in the two nitrate groups.

Q9　C　Mr(NH₄NO₃) = 28 + 4 + 48 = 80. Nitrogen = 2 × 14 = 28, so 28 ÷ 80 × 100% = 35.0%. 28.0% forgets to divide by Mr.

Q10　A　n(Mg) = 4.8 ÷ 24 = 0.20 mol. The mole ratio Mg : MgO is 1 : 1, so n(MgO) = 0.20 mol and m = 0.20 × 40 = 8.0 g. 4.8 g forgets the oxygen that is added.

Q11　B　Mole ratio: C 40.0 ÷ 12 = 3.33; H 6.7 ÷ 1 = 6.7; O 53.3 ÷ 16 = 3.33. Dividing by 3.33 gives 1 : 2 : 1, so the empirical formula is CH₂O (the empirical formula of glucose).

Q12　D　Q = It = 2.0 × 965 = 1 930 C; n(e⁻) = 1 930 ÷ 96 500 = 0.020 mol. Two moles of electrons give one mole of copper, so n(Cu) = 0.010 mol and m = 0.010 × 64 = 0.64 g.

Q13　A　n(Cu) = 1.28 ÷ 64 = 0.020 mol, so 0.040 mol of electrons is needed; Q = 0.040 × 96 500 = 3 860 C. 1 930 C forgets that each copper ion needs two electrons.

Q14　C　The overall reaction is 2H₂O → 2H₂ + O₂, so the volume (mole) ratio is 2 : 1. Cathode: 4H⁺ + 4e⁻ → 2H₂; anode: 2H₂O → O₂ + 4H⁺ + 4e⁻. For the same charge, twice as many moles of hydrogen are formed.

Q15　B　Bonds broken: 436 + 243 = 679 kJ. Bonds formed: 2 × 431 = 862 kJ. ΔH = 679 − 862 = −183 kJ/mol, so the reaction is exothermic.

Q16　D　n(H₂) = 2.0 ÷ 2.0 = 1.0 mol, so 286 kJ is released. 572 kJ comes from treating 2.0 g as 2 mol.

Q17　A　Rate = mass ÷ time = 0.60 ÷ 30 = 0.020 g/s. 18 g/s divides time by mass.

Q18　C　A catalyst provides an alternative route of lower activation energy. Both the forward and reverse reactions speed up equally, so the position of equilibrium, the yield and the enthalpy change are unchanged. The catalyst is not used up.

Q19　D　The left side has 4 mol of gas and the right side 2 mol. Raising the pressure shifts the equilibrium towards the side with fewer gas molecules, i.e. to the right, so the ammonia yield rises. This is why the Haber process uses high pressure.

Q20　B　Let the oxidation number of sulfur be x: 2 × (+1) + x + 4 × (−2) = 0, so x = +6. Hydrogen is +1 and oxygen is −2 here.

Q21　A　NaOH + HCl → NaCl + H₂O, a 1 : 1 ratio. n(NaOH) = 0.100 × 25.0 ÷ 1000 = 0.00250 mol, so c(HCl) = 0.00250 ÷ 0.0200 = 0.125 mol/dm³. 0.0800 mol/dm³ inverts the volume ratio.

Q22　C　Aluminium oxide is amphoteric: it forms an aluminium salt with acids and an aluminate with strong alkalis such as sodium hydroxide. Sodium oxide and calcium oxide are basic; sulfur dioxide is acidic.

Q23　B　Insoluble salts are made by precipitation: BaCl₂ + Na₂SO₄ → BaSO₄(s) + 2NaCl, then filter, wash and dry. Adding barium carbonate to acid is not the standard preparation.

Q24　D　n(CaCO₃) = 5.0 ÷ 100 = 0.050 mol. CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂ is 1 : 1, so V = 0.050 × 24 = 1.2 dm³. 0.050 dm³ treats the number of moles as a volume.

Q25　C　Group I metals have one outer electron. Going down the group the atoms get larger, so the outer electron is further from the nucleus and better shielded; less energy is needed to lose it and reactivity increases. These metals lose electrons, not gain them.

Q26　A　Reactivity falls down Group VII: fluorine > chlorine > bromine > iodine. That is why chlorine displaces bromide and iodide ions, while bromine displaces only iodide.

Q27　D　Helium is 2 (full), neon 2,8 (full) and argon 2,8,8 (full). A complete outer shell means no energetic gain from gaining or losing electrons, so they are very stable. They are monatomic gases, not diatomic molecules.

Q28　B　n(Ca) = 4.0 ÷ 40 = 0.10 mol and Ca : CaO is 1 : 1, so m(CaO) = 0.10 × 56 = 5.6 g, of which 1.6 g is the oxygen taken from the air.

Q29　C　Aluminium is more reactive than carbon, so carbon reduction does not work. Aluminium oxide is dissolved in molten cryolite (about 950 °C) and electrolysed: aluminium forms at the cathode and oxygen at the anode, which burns away the carbon anodes.

Q30　A　Mr(Fe₂O₃) = 112 + 48 = 160, so iron is 112 ÷ 160 = 0.70 by mass and 320 × 0.70 = 224 kg. 112 kg counts one mole of iron instead of two.

Q31　D　Brass is copper with zinc; bronze is copper with tin; steel is iron with carbon. Different-sized atoms in an alloy stop the layers sliding, so it is harder than the pure metal.

Q32　B　Zinc is more reactive than iron, so it is oxidised first and the iron is left intact: sacrificial protection, as with galvanised steel. Attaching copper speeds up rusting because iron then becomes the anode.

Q33　A　CH₄ + 2O₂ → CO₂ + 2H₂O gives 1 mol of CO₂ per mole of methane; Mr(CO₂) = 12 + 32 = 44, so 44 g. 16 g is the molar mass of methane itself.

Q34　C　Sulfur in coal burns to SO₂, which is oxidised further to SO₃ and dissolves in rain to give sulfuric acid; rain below pH 5.6 is acid rain. Controls include coal washing and flue-gas desulfurisation.

Q35　D　Mr = 5 × 12 + 12 × 1 = 60 + 12 = 72. The alkane formula is CₙH₂ₙ₊₂, and with n = 5 there are 12 hydrogen atoms. 58 is the Mr of butane, C₄H₁₀.

Q36　B　The ratio is 1 : 1, so n(Br₂) = 0.10 mol; Mr(Br₂) = 2 × 80 = 160 and m = 0.10 × 160 = 16 g. 160 g treats 1 mol as 0.10 mol.

Q37　A　Two: the straight chain butane, CH₃CH₂CH₂CH₃, and the branched 2-methylpropane. Propane, C₃H₈, has only one and pentane, C₅H₁₂, has three.

Q38　C　Mr(C₆H₁₂O₆) = 180, so n = 90 ÷ 180 = 0.50 mol. One mole of glucose gives two moles of ethanol, so n(ethanol) = 1.0 mol and m = 46 g; the other 44 g leaves as CO₂.

Q39　D　Rf = distance moved by the spot ÷ distance moved by the solvent front = 3.0 ÷ 8.0 = 0.375 ≈ 0.38. An Rf value is always below 1; 3.8 inverts the division.

Q40　B　Two miscible liquids with boiling points about 22 °C apart are separated by fractional distillation: repeated vaporisation and condensation in the column lets the lower-boiling ethanol leave at the top. Filtration removes insoluble solids and crystallisation recovers a dissolved solid.

Quick answer key

Grade guide (out of 40)

Suggested timing (45 minutes)

Notices

•　This paper has 40 four-option questions, 1 mark each, 40 marks in 45 minutes. There is no penalty for a wrong answer, so answer every question.

•　Choose exactly one option per question; multiple or blank responses score 0.

•　Unless stated otherwise, Ar: H 1, C 12, N 14, O 16, Na 23, Mg 24, Al 27, S 32, Cl 35.5, K 39, Ca 40, Fe 56, Cu 64, Br 80, Ba 137; 1 mol of electrons = 96 500 C; 1 mol of gas = 24 dm³ at room temperature and pressure.

•　Answers and explanations are in the answer PDF. Sit the whole paper before checking.

•　All questions are original and are not Cambridge past-paper questions; the grade bands are this paper’s own guide.

Related papers | 0620 Paper 2 exam technique and past-paper questions | 0620 Paper 4 theory paper | 0620 Paper 1 multiple choice (Core)

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This is original TutorZone practice material, not Cambridge past-paper content. The paper structure quoted (45 minutes, 40 four-option questions, 40 marks, 30% weighting) is taken from the Cambridge IGCSE Chemistry 0620 syllabus for 2026–2028, “Details of the assessment”.