Redox — Paper 1 · IGCSE Chemistry (9-1) 0971

14 Which equation shows an oxidation reaction? A C + O2 → CO2 B CaCO3 → CaO + CO2 C CaO + 2HCl → CaCl 2 + H2O D N2O4 → 2NO2

1 marks

Answer: A

This question in 0971/11 May/June 2018

25 In a blast furnace, iron ore is mixed with coke and limestone, and heated in hot air. Compound R is formed. Compound R then reduces the iron ore to iron. Which equation shows the formation of compound R? A C + O2 → CO2 B CO2 + C → 2CO C CaCO3 → CaO + CO2 D CaO + SiO2 → CaSiO3

1 marks

Answer: B

This question in 0971/11 May/June 2018

15 In a blast furnace, iron is extracted when iron(III) oxide reacts with carbon monoxide. The equation is shown. Fe2O3 + 3CO → 2Fe + 3CO2 Which substance is oxidised and which is reduced? oxidised reduced A CO Fe2O3 B CO2 Fe C Fe CO2 D Fe2O3 CO

1 marks

Answer: A

This question in 0971/11 May/June 2019

15 When magnesium is heated with zinc oxide a reaction occurs. The equation is shown. Mg + ZnO → MgO + Zn Which substance is oxidised? A magnesium B magnesium oxide C zinc D zinc oxide

1 marks

Answer: A

This question in 0971/12 Oct/Nov 2019

15 Carbon reacts with silver oxide to form carbon dioxide and silver. Which substance is reduced? A carbon B carbon dioxide C silver D silver oxide

1 marks

Answer: D

This question in 0971/11 May/June 2020

15 When heated strongly, silicon(IV) oxide reacts with carbon. SiO2 + 2C → Si + 2CO Which term describes what happens to silicon(IV) oxide? A thermal decomposition B neutralisation C oxidation D reduction

1 marks

Answer: D

This question in 0971/12 May/June 2020

19 During the manufacture of sulfuric acid, sulfur dioxide is converted to sulfur trioxide. 2SO2 + O2  2SO3 Which type of reaction is this? A displacement B neutralisation C oxidation D thermal decomposition

1 marks

Answer: C

This question in 0971/12 Oct/Nov 2020

20 Some reactions of element M are shown. burn add water element M oxide of M solution add to purple acidified add blue litmus potassium manganate(VII) goes colourless goes red What is element M? A carbon B iron C magnesium D sulfur

1 marks

Answer: D

This question in 0971/11 May/June 2021

16 What happens to a chemical substance when it is reduced? A It burns. B It decomposes. C It loses oxygen. D It gains mass.

1 marks

Answer: C

This question in 0971/12 Oct/Nov 2021

16 In which equation is carbon both oxidised and reduced? A C + O2  CO2 B CO2 + C  2CO C 3CO + Fe2O3  3CO2 + 2Fe D 2CO + O2  2CO2

1 marks

Answer: B

This question in 0971/12 May/June 2022

16 When magnesium is heated with zinc oxide a reaction occurs. The equation is shown. Mg + ZnO  MgO + Zn Which substance is oxidised? A magnesium B magnesium oxide C zinc D zinc oxide

1 marks

Answer: A

This question in 0971/12 Oct/Nov 2022

14 Four redox equations and statements about the equations are shown. reaction statement 1 C + O2 → CO2 carbon is oxidised 2 CO2 + C → 2CO carbon dioxide is oxidised 3 CO2 + C → 2CO carbon is oxidised 4 Fe2O3 + 3CO → 2Fe + 3CO2 iron(III) oxide is oxidised Which statements about the equations are correct? A 1 and 2 B 1 and 3 C 2 and 4 D 3 and 4

1 marks

Answer: B

This question in 0971/11 May/June 2023

14 The equation for the reaction between iron(III) oxide and carbon is shown. 2Fe2O3 + 3C → 4Fe + 3CO2 Which type of reaction does iron(III) oxide undergo? A reduction B precipitation C oxidation D combustion

1 marks

Answer: A

This question in 0971/12 May/June 2023

17 In a blast furnace, iron(III) oxide is converted to iron and carbon monoxide is converted to carbon dioxide. Fe2O3 + 3CO → 2Fe + 3CO2 What happens to each of these reactants? A Both iron(III) oxide and carbon monoxide are oxidised. B Both iron(III) oxide and carbon monoxide are reduced. C Iron(III) oxide is oxidised and carbon monoxide is reduced. D Iron(III) oxide is reduced and carbon monoxide is oxidised.

1 marks

Answer: D

This question in 0971/12 Oct/Nov 2023

8 Iron(III) oxide is reduced by carbon monoxide to produce iron and carbon dioxide. What is the balanced equation for this reaction? A Fe2O3 + 2CO →2Fe + 2CO2 B Fe2O3 + 3CO →2Fe + 3CO2 C 2Fe2O3 + 6CO →2Fe + 6CO2 D 2Fe2O3 + 3CO →4Fe + 3CO2

1 marks

Answer: B

This question in 0971/11 May/June 2024

11 Which statements about a hydrogen–oxygen fuel cell are correct? 1 The main form of energy released by the fuel cell is heat. 2 The reaction is a redox reaction. 3 An acidic gas is produced. 4 Water is the only chemical product. A 1 and 3 B 1 and 4 C 2 and 3 D 2 and 4

1 marks

Answer: D

This question in 0971/11 May/June 2024

17 Which equation represents an oxidation reaction? A CaCO3 →CaO + CO2 B 4FeO + O2 →2Fe2O3 C 2NO2 →N2O4 D 2P2O5 →P4O10

1 marks

Answer: B

This question in 0971/11 May/June 2024

19 Which of the reactions show the underlined substance being reduced? 1 CuO + H2 →Cu + H2O 2 2Mg + O2 →2MgO 3 MgO + 2HCl →MgCl2 + H2O A 1 and 2 B 1 only C 2 and 3 D 3 only

1 marks

Answer: B

This question in 0971/12 May/June 2024

19 The equation for the reaction of magnesium with copper(II) oxide is shown. Mg + CuO  MgO + Cu Which word describes this reaction? A combustion B decomposition C neutralisation D redox

1 marks

Answer: D

This question in 0971/12 Oct/Nov 2024

25 Zinc is formed when zinc oxide is heated with carbon. zinc oxide + carbon  zinc + carbon monoxide Which substance is oxidised in this reaction? A carbon B carbon monoxide C zinc D zinc oxide

1 marks

Answer: A

This question in 0971/12 Oct/Nov 2024

16 The equation for the reaction between copper(II) oxide and carbon is shown. 2CuO + C  2Cu + CO2 Which statement about this reaction is correct? A CuO is reduced. B CO2 is oxidised. C Cu is oxidised. D C is reduced.

1 marks

Answer: A

This question in 0971/11 May/June 2025

18 Which reactions are redox reactions? 1 the incomplete combustion of propane 2 the rusting of iron 3 the reaction of aqueous chloride ions with acidified aqueous silver nitrate 4 the thermal decomposition of calcium carbonate A 1 and 2 B 1 and 3 C 2 and 4 D 3 and 4

1 marks

Answer: A

This question in 0971/12 May/June 2025

18 What is the oxidation number of iron in iron(III) oxide, Fe2O3? A +2 B +3 C –2 D –3

1 marks

Answer: B

This question in 0971/12 Oct/Nov 2025