The mole and the Avogadro constant — Paper 2 · IGCSE Chemistry (9-1) 0971

8 The equation for the combustion of ethane is shown. 2C2H6 + 7O2 → 4CO2 + 6H2O Which volume of carbon dioxide, at room temperature and pressure, is formed when 0.5 moles of ethane burn? A 48 dm3 B 24 dm3 C 12 dm3 D 6 dm3

1 marks

Answer: B

This question in 0971/21 May/June 2018

9 A solution of ethanoic acid, CH3COOH, has a concentration of 2 mol / dm3. Which statement about this solution is correct? A 20 g of ethanoic acid is dissolved in 10 cm3 of water. B 30 g of ethanoic acid is dissolved in 250 cm3 of water. C 60 g of ethanoic acid is dissolved in 1 dm3 of water. D 120 g of ethanoic acid is dissolved in 2 dm3 of water.

1 marks

Answer: B

This question in 0971/21 May/June 2018

7 Which gas sample contains the smallest number of molecules? A 4 g of helium B 16 g of oxygen C 28 g of carbon monoxide D 28 g of nitrogen

1 marks

Answer: B

This question in 0971/22 Oct/Nov 2018

8 The equation for the reaction between calcium carbonate and dilute nitric acid is shown. CaCO3(s) + 2HNO3(aq) → Ca(NO3)2(aq) + CO2(g) + H2O(l) 25 g of calcium carbonate is reacted with an excess of dilute nitric acid. Which mass of calcium nitrate and which volume of carbon dioxide is produced at room temperature and pressure? mass of volume of calcium nitrate / g carbon dioxide / dm3 A 29 6 B 29 12 C 41 6 D 41 12

1 marks

Answer: C

This question in 0971/22 Oct/Nov 2018

8 A tablet contains 0.080 g of ascorbic acid (Mr = 176). What is the concentration of ascorbic acid when one tablet is dissolved in 200 cm3 of water? A 9.1 × 10–5 mol / dm3 B 4.5 × 10–4 mol / dm3 C 9.1 × 10–2 mol / dm3 D 2.3 × 10–3 mol / dm3

1 marks

Answer: D

This question in 0971/21 May/June 2019

9 Phosphorus reacts with oxygen to form phosphorus(III) oxide as shown. 4P(s) + 3O2(g) → 2P2O3(s) Which mass of phosphorus(III) oxide is produced from 6.2 g of phosphorus? A 1.1 g B 5.5 g C 11.0 g D 22.0 g

1 marks

Answer: C

This question in 0971/22 Oct/Nov 2019

10 Calcium carbonate is heated. Calcium oxide and carbon dioxide gas are formed. The equation for the reaction is shown. CaCO3 → CaO + CO2 225 kg of calcium carbonate is heated until there is no further change in mass. The yield of calcium oxide is 85 kg. What is the percentage yield? A 37.8% B 47.2% C 67.5% D 85.0%

1 marks

Answer: C

This question in 0971/22 Oct/Nov 2019

9 The Haber process is a reversible reaction. N2(g) + 3H2(g) 2NH3(g) The reaction has a 30% yield of ammonia. Which volume of ammonia gas, NH3, measured at room temperature and pressure, is obtained by reacting 0.75 moles of hydrogen with excess nitrogen? A 3600 cm3 B 5400 cm3 C 12 000 cm3 D 18 000 cm3

1 marks

Answer: A

This question in 0971/21 May/June 2020

9 The Haber process is a reversible reaction. N2(g) + 3H2(g) 2NH3(g) The reaction has a 30% yield of ammonia. Which volume of ammonia gas, NH3, measured at room temperature and pressure, is obtained by reacting 0.75 moles of hydrogen with excess nitrogen? A 3600 cm3 B 5400 cm3 C 12 000 cm3 D 18 000 cm3

1 marks

Answer: A

This question in 0971/22 May/June 2020

13 What is the empirical formula of an oxide of iron, formed by reacting 2.24 g of iron with 0.96 g of oxygen? A FeO B Fe2O C Fe2O3 D Fe3O4

1 marks

Answer: C

This question in 0971/22 Oct/Nov 2020

15 Hydrogen reacts with oxygen in a fuel cell. 2H2 + O2  2H2O The reaction is exothermic. 286 kJ of energy is released for every mole of water formed. Which volume of hydrogen gas, measured at room temperature and pressure, would react with oxygen with the release of 7000 J of energy? A 587 cm3 B 1175 cm3 C 587 dm3 D 1175 dm3

1 marks

Answer: A

This question in 0971/22 Oct/Nov 2020

34 The element sulfur is found in a number of different minerals. Which mineral contains the greatest percentage by mass of sulfur? A barite, BaSO4 B galena, PbS C gypsum, CaSO4 D pyrite, FeS2

1 marks

Answer: D

This question in 0971/22 Oct/Nov 2020

9 2.56 g of a metal oxide, MO2, is reduced to 1.92 g of the metal, M. What is the relative atomic mass of M? A 48 B 96 C 128 D 192

1 marks

Answer: B

This question in 0971/21 May/June 2021

9 Chlorine gas will react with iron metal. Exactly 21.3 g of chlorine reacts with 11.2 g of iron. How many iron atoms react with 30 molecules of chlorine? A 10 B 15 C 20 D 30

1 marks

Answer: C

This question in 0971/22 May/June 2021

9 The equation for the reaction of sodium with water is shown. 2Na + 2H2O  2NaOH + H2 What is the volume of hydrogen gas, measured at r.t.p., produced when 18.4 g of sodium reacts with excess water? A 9.6 dm3 B 15.0 dm3 C 19.2 dm3 D 30.0 dm3

1 marks

Answer: A

This question in 0971/22 Oct/Nov 2021

9 The equation for the reaction between aqueous lead(II) nitrate and aqueous sodium chloride is shown. Pb(NO3)2(aq) + 2NaCl (aq)  PbCl 2(s) + 2NaNO3(aq) If 100 cm3 of aqueous lead(II) nitrate of concentration 0.1 mol / dm3 is reacted with an excess of aqueous sodium chloride, which mass of lead(II) chloride is obtained? A 1.16 g B 2.42 g C 2.78 g D 3.31 g

1 marks

Answer: C

This question in 0971/21 May/June 2022

8 Methane and steam react in the presence of a catalyst. CH4(g) + H2O(g)  CO(g) + 3H2(g) 0.5 mol of methane reacts completely with 0.5 mol of steam. What is the volume of carbon monoxide and hydrogen produced, measured at room temperature and pressure? volume volume of CO / dm3 of H2 / dm3 A 0.5 1.5 B 1.0 3.0 C 12.0 12.0 D 12.0 36.0

1 marks

Answer: D

This question in 0971/22 May/June 2022

17 When a hydrogen–oxygen fuel cell is in operation, a different reaction happens at each electrode. at the hydrogen electrode H2  2H+ + 2e– at the oxygen electrode O2 + 2H2O + 4e–  4OH– The electrons that are lost at the hydrogen electrode travel through the external circuit to the oxygen electrode, where they are gained by the oxygen and water. A hydrogen–oxygen fuel cell is operated for a period of time and four moles of oxygen molecules are consumed. Which mass of hydrogen is consumed? A 2.0 g B 4.0 g C 8.0 g D 16.0 g

1 marks

Answer: D

This question in 0971/22 May/June 2022

9 Which sample does not contain a number of atoms equal to the Avogadro constant? A 14 g of nitrogen, N2 B 6 g of water, H2O C 4 g of helium, He D 28 g of carbon monoxide, CO

1 marks

Answer: D

This question in 0971/22 Oct/Nov 2022

8 Heating iron sulfide, FeS2, in air produces sulfur dioxide. 4FeS2 + 11O2 → 2Fe2O3 + 8SO2 What is the maximum mass of sulfur dioxide produced from 120 kg of iron sulfide? A 64 kg B 128 kg C 240 kg D 512 kg

1 marks

Answer: B

This question in 0971/21 May/June 2023

7 Which sample contains the largest number of molecules? A 16 g of methane, CH4(g) B 16 g of oxygen, O2(g) C 16 g of phosphorus, P4(s) D 16 dm3 of methane at r.t.p., CH4(g)

1 marks

Answer: A

This question in 0971/22 May/June 2023

10 When heated, copper(II) oxide, CuO, reacts with ammonia, NH3. 3CuO + 2NH3 →3Cu + N2 + 3H2O 8.5g of ammonia reacts with an excess of copper(II) oxide to produce 26.4g of copper. What is the percentage yield of copper in this reaction? A 27.5% B 32.2% C 55.0% D 82.5%

1 marks

Answer: C

This question in 0971/21 May/June 2024

12 Magnesium chloride, MgCl 2, contains magnesium ions and chloride ions. How many chloride ions are present in two moles of magnesium chloride? A 6.02 × 1023 B 1.204 × 1024 C 2.408 × 1024 D 3.612 × 1024

1 marks

Answer: C

This question in 0971/21 May/June 2024

10 The equation for the decomposition of ammonium carbonate, (NH4)2CO3, is shown. (NH4)2CO3(s)  2NH3(g) + CO2(g) + H2O(l) [Mr: (NH4)2CO3, 96] The total volume of gas produced is 360 cm3 at r.t.p. Which mass of ammonium carbonate, (NH4)2CO3, is decomposed? A 0.24 g B 0.48 g C 0.96 g D 1.44 g

1 marks

Answer: B

This question in 0971/22 Oct/Nov 2024

7 When 65 g of zinc reacts with 32 g of sulfur, 97 g of zinc sulfide is produced. When 65 g of zinc reacts with 40 g of sulfur, the mass of zinc sulfide produced is still 97 g. Which statement explains this observation? A Some of the zinc sulfide evaporates. B The reaction rate is slow. C The reaction stops before it is complete. D Zinc is the limiting reactant.

1 marks

Answer: D

This question in 0971/22 May/June 2025

9 The concentration of a solution of aqueous sodium hydroxide is 0.50 mol / dm3. Which mass of sodium hydroxide is used to make 500 cm3 of this solution? A 10 g B 20 g C 40 g D 160 g

1 marks

Answer: A

This question in 0971/22 May/June 2025

10 The equation for the combustion of ethanol is shown. C2H5OH + 3O2  2CO2 + 3H2O The relative molecular mass, Mr, of ethanol is 46. Which statement about the reaction is correct? A 4.6 g of ethanol produces 4.4 g of carbon dioxide. B 92 g of ethanol produces 88 g of carbon dioxide and 108 g of water. C 138 g of ethanol reacts with 32 g of oxygen. D 184 g of ethanol produces 216 g of water.

1 marks

Answer: D

This question in 0971/22 Oct/Nov 2025