Total marks: 40 · Duration: 45 minutes
Instructions to candidates
- There are forty questions in this paper. Answer all questions.
- For each question there are four possible answers, A, B, C and D. Choose the one you consider correct.
- Each correct answer scores one mark. No marks are deducted for a wrong answer.
- Any working should be done on rough paper. You may use a calculator.
- Relative atomic masses are given in the questions where they are needed. One mole of any gas occupies 24 dm³ at room temperature and pressure (r.t.p.).
- This paper covers the Extended content of the Cambridge IGCSE Chemistry syllabus.
Paper
Multiple choice (40 marks)
1. Four gases are released at the same moment from one end of a long tube at the same temperature. Which gas reaches the other end first?
A) carbon dioxide, Mr = 44 B) methane, Mr = 16 C) oxygen, Mr = 32 D) nitrogen, Mr = 28
2. Bromine has a melting point of −7 °C and a boiling point of 59 °C. What is its physical state at 0 °C?
A) solid B) gas C) a mixture of solid and gas D) liquid
3. A sealed metal can of gas is heated. Why does the pressure inside the can increase?
A) The particles move faster and hit the walls more often and with more force. B) The particles expand and take up more of the space inside the can. C) Extra gas particles are formed as the temperature rises. D) The particles are attracted more strongly to the walls of the can.
4. An atom of element X contains 19 protons and 20 neutrons. Which statement about X is correct?
A) Its nucleon number is 20. B) It is in Group VII of the Periodic Table. C) It forms X⁺ ions that contain 18 electrons. D) Its electronic configuration is 2,8,8,2.
5. Which pair of particles are isotopes of the same element?
A) carbon-14 and nitrogen-14 B) an oxygen molecule, O₂, and an ozone molecule, O₃ C) chlorine-35 and chlorine-37 D) a sodium atom and a sodium ion
6. Which substance has a giant covalent structure?
A) silicon(IV) oxide B) sodium chloride C) methane D) copper
7. Why does graphite conduct electricity?
A) It contains ions that are free to move. B) Its carbon atoms are joined by strong covalent bonds. C) Its layers can slide over one another. D) Each carbon atom has one electron that is delocalised.
8. Which statement describes metallic bonding?
A) Pairs of electrons are shared between neighbouring atoms. B) Positive ions are attracted to a sea of delocalised electrons. C) Negative ions are attracted to a lattice of positive nuclei. D) Oppositely charged ions attract each other in a lattice.
9. What is the formula of aluminium sulfate?
A) Al₂(SO₄)₃ B) AlSO₄ C) Al₃(SO₄)₂ D) Al₂SO₄
10. How many moles of oxygen atoms are present in 0.20 mol of calcium nitrate, Ca(NO₃)₂?
A) 0.60 B) 0.20 C) 1.2 D) 2.4
11. 6.0 g of magnesium burns completely in air: 2Mg + O₂ → 2MgO. What mass of magnesium oxide is formed? (Ar: Mg = 24, O = 16)
A) 4.0 g B) 6.0 g C) 8.0 g D) 10 g
12. Methane burns completely: CH₄ + 2O₂ → CO₂ + 2H₂O. What volume of oxygen, at r.t.p., is needed to burn 0.10 mol of methane?
A) 2.4 dm³ B) 4.8 dm³ C) 7.2 dm³ D) 9.6 dm³
13. A hydrocarbon contains 85.7% carbon and 14.3% hydrogen by mass. Its relative molecular mass is 42. What is its molecular formula? (Ar: C = 12, H = 1)
A) CH₂ B) C₃H₆ C) C₂H₄ D) C₃H₈
14. Concentrated aqueous sodium chloride is electrolysed using inert electrodes. What is formed at each electrode?
A) oxygen at the anode and sodium at the cathode B) chlorine at the anode and sodium at the cathode C) hydrogen at the anode and chlorine at the cathode D) chlorine at the anode and hydrogen at the cathode
15. Molten lead(II) bromide is electrolysed. Which ionic half-equation shows the reaction at the cathode?
A) Pb²⁺ + 2e⁻ → Pb B) 2Br⁻ → Br₂ + 2e⁻ C) Pb → Pb²⁺ + 2e⁻ D) Br₂ + 2e⁻ → 2Br⁻
16. What is the only chemical product of a hydrogen–oxygen fuel cell?
A) carbon dioxide B) hydrogen peroxide C) water D) oxygen
17. Impure copper is purified by electrolysis, using aqueous copper(II) sulfate as the electrolyte. Which statement is correct?
A) The pure copper is used as the anode. B) The impure copper anode loses mass. C) Oxygen is given off at the cathode. D) The electrolyte gradually turns colourless.
18. Hydrogen reacts with chlorine: H₂ + Cl₂ → 2HCl. The bond energies are H–H 436 kJ/mol, Cl–Cl 242 kJ/mol and H–Cl 431 kJ/mol. What is the energy change for the reaction?
A) −184 kJ/mol B) +184 kJ/mol C) −247 kJ/mol D) +247 kJ/mol
19. Which statement describes an endothermic reaction?
A) The temperature of the surroundings rises and ΔH is negative. B) The products have less energy than the reactants. C) ΔH is positive and the surroundings become cooler. D) More energy is released making bonds than is used breaking them.
20. Marble chips react with dilute hydrochloric acid. Which change does NOT increase the rate of the reaction?
A) using the same mass of powdered marble B) heating the acid before adding it C) using more concentrated acid D) using a larger volume of the same acid
21. Why does increasing the temperature increase the rate of a reaction?
A) The particles gain mass and collide harder. B) The activation energy of the reaction decreases. C) More reactant particles are formed. D) A greater proportion of collisions have at least the activation energy.
22. In the Contact process, 2SO₂(g) + O₂(g) ⇌ 2SO₃(g). The forward reaction is exothermic. Which conditions would give the highest equilibrium yield of sulfur trioxide?
A) high temperature and low pressure B) high temperature and high pressure C) low temperature and high pressure D) low temperature and low pressure
23. Which reaction is a redox reaction?
A) Zn + CuSO₄ → ZnSO₄ + Cu B) NaOH + HCl → NaCl + H₂O C) CaCO₃ → CaO + CO₂ D) AgNO₃ + NaCl → AgCl + NaNO₃
24. In the blast furnace, Fe₂O₃ + 3CO → 2Fe + 3CO₂. Which substance is the reducing agent?
A) Fe₂O₃ B) CO C) Fe D) CO₂
25. Solutions of ethanoic acid and hydrochloric acid have the same concentration. Which statement is correct?
A) The hydrochloric acid has the higher pH. B) The ethanoic acid is fully ionised in water. C) The hydrochloric acid has a higher concentration of H⁺ ions. D) The ethanoic acid reacts faster with magnesium ribbon.
26. Which oxide is amphoteric?
A) sodium oxide, Na₂O B) aluminium oxide, Al₂O₃ C) sulfur dioxide, SO₂ D) carbon monoxide, CO
27. Which method is best for preparing a pure, dry sample of insoluble barium sulfate?
A) Add excess barium carbonate to dilute sulfuric acid, filter, then crystallise the filtrate. B) Titrate barium hydroxide with sulfuric acid, then evaporate all the water. C) Heat barium metal strongly with powdered sulfur. D) Mix solutions of barium chloride and sodium sulfate, then filter, wash and dry the precipitate.
28. A few drops of aqueous sodium hydroxide are added to a solution, and a red-brown precipitate forms. Which ion is present?
A) Fe³⁺ B) Fe²⁺ C) Cu²⁺ D) Zn²⁺
29. An element has the electronic configuration 2,8,7. Which statement about the element is correct?
A) It forms ions with a charge of 1−. B) It is a metal. C) It is in Period 2. D) It is in Group I.
30. Which property is typical of transition elements?
A) They have low densities. B) They react vigorously with cold water. C) They form only colourless compounds. D) They and their compounds often act as catalysts.
31. Rubidium is below potassium in Group I. Which prediction about rubidium is correct?
A) It reacts less vigorously with water than potassium. B) It reacts more vigorously with water than potassium. C) It has a higher melting point than potassium. D) It forms ions with a 2+ charge.
32. Metal M does not react with cold water, but it displaces copper from aqueous copper(II) sulfate. Which metal could M be?
A) potassium B) sodium C) zinc D) silver
33. Why is aluminium extracted by electrolysis rather than by heating its oxide with carbon?
A) Aluminium is less reactive than carbon. B) Aluminium oxide is insoluble in water. C) Carbon would react with the cryolite. D) Aluminium is more reactive than carbon.
34. Iron is galvanised by coating it with zinc. Why is the iron still protected when the zinc layer is scratched?
A) Zinc is more reactive than iron, so the zinc corrodes instead. B) Zinc is less reactive than iron, so it pushes water away. C) Zinc reacts with the iron to form a rust-proof alloy. D) Zinc repels the oxygen in the air from the scratch.
35. Which gas is produced by the incomplete combustion of fuels and is toxic because it reduces the blood's ability to carry oxygen?
A) carbon dioxide B) carbon monoxide C) nitrogen D) methane
36. Which compound supplies two of the three main plant nutrients, nitrogen, phosphorus and potassium?
A) ammonium nitrate, NH₄NO₃ B) potassium chloride, KCl C) potassium nitrate, KNO₃ D) calcium phosphate, Ca₃(PO₄)₂
37. Which compound is an alkene?
A) C₃H₆ B) C₃H₈ C) C₂H₅OH D) CH₃COOH
38. Ethene reacts with steam, in the presence of a catalyst, to form ethanol. What type of reaction is this?
A) substitution B) condensation C) cracking D) addition
39. Decane is cracked: C₁₀H₂₂ → C₈H₁₈ + X. What is X?
A) CH₄ B) C₂H₆ C) C₂H₄ D) C₃H₆
40. Which statement describes how nylon, a polyamide, is formed?
A) Alkene monomers join by addition polymerisation. B) Monomers join by condensation polymerisation, losing water. C) Glucose is fermented by yeast. D) Long-chain alkanes are cracked into shorter ones.