2 (a) Copper and sodium are metals. Copper is a transition element. Sodium is not a transition element. It is found in Group I of the Periodic Table. Some properties of metallic elements are listed. A act as a catalyst B form coloured compounds C good conductor of electricity D good conductor of thermal energy E malleable F non-magnetic State the letters (A to F) of the two properties that describe copper but do not describe sodium. … and … [2] (b) Copper(II) oxide is heated with carbon. Copper and carbon dioxide are made. (i) Construct the word equation for the reaction between copper(II) oxide and carbon. + + [1] (ii) State the chemical test for carbon dioxide gas and the observation for a positive result. test … observation … [2] (iii) Explain why copper(II) oxide is described as a basic oxide. … … [1] (c) Metals can be coated with a layer of copper using electroplating. Electroplating uses the process of electrolysis. Use words from the list to complete the sentence to define the term electrolysis. Each word may be used once or not at all. covalent electricity gas ionic molten solid solution time water Electrolysis always involves the breakdown of … compounds when … or in aqueous … by the passage of … . [2] (d) Bronze is a mixture of copper and tin. (i) State the term used to describe a mixture of metals. … [1] (ii) Apart from cost, suggest why bronze is used to make coins but pure copper is not used to make coins. … … [1] [Total: 10]

2(a) A; B; 2 2(b)(i) copper oxide + carbon → copper + carbon dioxide; 1 2(b)(ii) (bubble through) limewater; goes cloudy / milky; 2 2(b)(iii) produces solution with pH above 7 / copper(II) oxide is a metal oxide; 1 2(c) ionic molten solution electricity;; 2 2(d)(i) alloy; 1 2(d)(ii) tougher / stronger; 1 (a) To earn the marks, you must state both 'A' and 'B' as the properties that describe copper but not sodium. (b)(i) To earn the mark, you must write the complete and correct word equation: copper oxide + carbon → copper + carbon dioxide. (b)(ii) To earn the marks, you must state 'limewater' as the test and 'goes cloudy/milky' as the observation for carbon dioxide. (b)(iii) To earn the mark, you must explain that copper(II) oxide is a basic oxide because it produces a solution with a pH above 7 or is a metal oxide. (c) To earn the marks, you must correctly identify 'ionic', 'molten', 'solution', and 'electricity' as the conditions for electrolysis. (d)(i) To earn the mark, you must state 'alloy' as the term for a mixture of metals. (d)(ii) To earn the mark, you must state that an alloy is 'tougher' or 'stronger' than a pure metal.

2 (a) Magnesium is in Period 3 of the Periodic Table. (i) Use the Periodic Table to name the noble gas in Period 3 of the Periodic Table. … [1] (ii) Describe the change in metallic character across Period 3. … … [1] (b) Magnesium reacts with carbon dioxide. Magnesium oxide and carbon are made. (i) Write the word equation for this reaction. … + … … + … [1] (ii) The reaction between magnesium and carbon dioxide is exothermic. Explain what is meant by an exothermic reaction. … … [1] (c) An atom of magnesium has a proton number (atomic number) of 12 and a nucleon number (mass number) of 24. Complete Table 2.1 to show the names and numbers of the two particles contained in the nucleus of this magnesium atom. Table 2.1 name of particle number of particles [2] (d) Magnesium carbonate reacts with dilute hydrochloric acid to make aqueous magnesium chloride. (i) Magnesium carbonate is insoluble in water. State the separation technique used to remove magnesium carbonate from a mixture of magnesium carbonate and water. … [1] (ii) Magnesium chloride dissolves in water. State the separation technique used to obtain solid magnesium chloride from a solution of magnesium chloride. … [1] (iii) Magnesium carbonate reacts with dilute hydrochloric acid. Complete the balanced symbol equation for this reaction. MgCO3 + …HCl MgCl 2 + CO2 + H2O [1] (iv) Dilute hydrochloric acid contains aqueous chloride ions. State the test for aqueous chloride ions and give the observation for a positive result. test … observation … [2] (e) Table 2.2 shows the composition of a magnesium alloy. Table 2.2 element % by mass magnesium 94 neodymium 2 yttrium 4 (i) Calculate the mass of magnesium in 500 kg of the alloy. … kg [1] (ii) The alloy is used in aircraft bodies. Suggest why the alloy of magnesium is used rather than pure magnesium for aircraft bodies. … … [1] [Total: 13]

2(a)(i) argon ; 1 2(a)(ii) metal to non-metal ; 1 2(b)(i) magnesium + carbon dioxide → carbon + magnesium oxide ; 1 2(b)(ii) thermal energy released ; 1 2(c) protons –12 ; neutrons –12 ; 2 2(d)(i) filtration ; 1 2(d)(ii) crystallisation ; 1 2(d)(iii) MgCO3 + 2HCl → MgCl2 + CO2 + H2O ; 1 2(d)(iv) (acidified) (aqueous) silver nitrate ; white precipitate ; 2 2(e)(i) 470 (kg) ; 1 2(e)(ii) stronger / less dense ; 1 (a)(i) To earn this mark, you must correctly identify 'argon' as the noble gas in Period 3. (a)(ii) To earn this mark, you must describe the change in metallic character across Period 3 as going from 'metal to non-metal'. (b)(i) To earn this mark, you must write the correct word equation: 'magnesium + carbon dioxide → carbon + magnesium oxide'. (b)(ii) To earn this mark, you must explain that an exothermic reaction is one where 'thermal energy is released'. (c) To earn these two marks, you must correctly state that the nucleus contains 'protons – 12' and 'neutrons – 12'. (d)(i) To earn this mark, you must identify 'filtration' as the correct separation technique. (d)(ii) To earn this mark, you must identify 'crystallisation' as the correct separation technique. (d)(iii) To earn this mark, you must write the correct balanced chemical equation: 'MgCO3 + 2HCl → MgCl2 + CO2 + H2O'. (d)(iv) To earn these two marks, you must state the use of '(acidified) (aqueous) silver nitrate' and observe a 'white precipitate'. (e)(i) To earn this mark, you must state the correct value '470 (kg)'. (e)(ii) To earn this mark, you must state that the alloy is 'stronger / less dense' than pure magnesium.

2 (a) Magnesium is in Period 3 of the Periodic Table. (i) Use the Periodic Table to name the noble gas in Period 3 of the Periodic Table. … [1] (ii) Describe the change in metallic character across Period 3. … … [1] (b) Magnesium reacts with carbon dioxide. Magnesium oxide and carbon are made. (i) Write the word equation for this reaction. … + … … + … [1] (ii) The reaction between magnesium and carbon dioxide is exothermic. Explain what is meant by an exothermic reaction. … … [1] (c) An atom of magnesium has a proton number (atomic number) of 12 and a nucleon number (mass number) of 24. Complete Table 2.1 to show the names and numbers of the two particles contained in the nucleus of this magnesium atom. Table 2.1 name of particle number of particles [2] (d) Magnesium carbonate reacts with dilute hydrochloric acid to make aqueous magnesium chloride. (i) Magnesium carbonate is insoluble in water. State the separation technique used to remove magnesium carbonate from a mixture of magnesium carbonate and water. … [1] (ii) Magnesium chloride dissolves in water. State the separation technique used to obtain solid magnesium chloride from a solution of magnesium chloride. … [1] (iii) Magnesium carbonate reacts with dilute hydrochloric acid. Complete the balanced symbol equation for this reaction. MgCO3 + …HCl MgCl 2 + CO2 + H2O [1] (iv) Dilute hydrochloric acid contains aqueous chloride ions. State the test for aqueous chloride ions and give the observation for a positive result. test … observation … [2] (e) Table 2.2 shows the composition of a magnesium alloy. Table 2.2 element % by mass magnesium 94 neodymium 2 yttrium 4 (i) Calculate the mass of magnesium in 500 kg of the alloy. … kg [1] (ii) The alloy is used in aircraft bodies. Suggest why the alloy of magnesium is used rather than pure magnesium for aircraft bodies. … … [1] [Total: 13]

2(a)(i) argon ; 1 2(a)(ii) metal to non-metal ; 1 2(b)(i) magnesium + carbon dioxide → carbon + magnesium oxide ; 1 2(b)(ii) thermal energy released ; 1 2(c) protons –12 ; neutrons –12 ; 2 2(d)(i) filtration ; 1 2(d)(ii) crystallisation ; 1 2(d)(iii) MgCO3 + 2HCl → MgCl2 + CO2 + H2O ; 1 2(d)(iv) (acidified) (aqueous) silver nitrate ; white precipitate ; 2 2(e)(i) 470 (kg) ; 1 2(e)(ii) stronger / less dense ; 1 (a)(i) To earn this mark, you must correctly identify 'argon' as the noble gas in Period 3. (a)(ii) To earn this mark, you must describe the change in metallic character across Period 3 as going from 'metal to non-metal'. (b)(i) To earn this mark, you must write the correct word equation: 'magnesium + carbon dioxide → carbon + magnesium oxide'. (b)(ii) To earn this mark, you must explain that an exothermic reaction is one where 'thermal energy is released'. (c) To earn these two marks, you must correctly state that the nucleus contains 'protons – 12' and 'neutrons – 12'. (d)(i) To earn this mark, you must identify 'filtration' as the correct separation technique. (d)(ii) To earn this mark, you must identify 'crystallisation' as the correct separation technique. (d)(iii) To earn this mark, you must write the correct balanced chemical equation: 'MgCO3 + 2HCl → MgCl2 + CO2 + H2O'. (d)(iv) To earn these two marks, you must state the use of '(acidified) (aqueous) silver nitrate' and observe a 'white precipitate'. (e)(i) To earn this mark, you must state the correct value '470 (kg)'. (e)(ii) To earn this mark, you must state that the alloy is 'stronger' or 'less dense' than pure magnesium.

2 (a) The thermal decomposition of calcium carbonate makes calcium oxide and carbon dioxide. (i) Write the word equation for the thermal decomposition of calcium carbonate. + [1] (ii) The production of lime (calcium oxide) from limestone (calcium carbonate) is one use of limestone. State one other use of limestone. … [1] (iii) Calcium carbonate has the formula CaCO3. State the number of different elements present in calcium carbonate. … [1] (iv) Explain why the thermal decomposition of calcium carbonate is a chemical change and not a physical change. … … [1] (v) The thermal decomposition of calcium carbonate is an endothermic reaction. State what is meant by an endothermic reaction. … … … [1] (b) (i) Carbon dioxide is a compound but carbon is an element. State the difference between an element and a compound. … … … [2] (ii) Carbon is a solid and carbon dioxide is a gas. Complete Table 2.1 to describe the differences between a solid and a gas. One difference has been done for you. Table 2.1 particle separation particle arrangement particle motion solid vibrate about a fixed point gas move rapidly in all directions [2] (c) Carbon exists in many forms including diamond and graphite. Diamond and graphite are described as giant covalent structures. Fig. 2.1 shows three covalent structures, A, B and C. A B C carbon atom Fig. 2.1 (i) State which structure represents diamond. Choose from A, B or C. … [1] (ii) State which structure represents graphite. Choose from A, B or C. … [1] (iii) State why the bonding between the carbon atoms in diamond is covalent and not ionic. … … [1] [Total: 12]

2(a)(i) calcium carbonate → calcium oxide + carbon dioxide ; 1 2(a)(ii) neutralizing acidic soil / building material / cement ; 1 2(a)(iii) 3 ; 1 2(a)(iv) new substances produced ; 1 2(a)(v) (thermal) energy taken in ; 1 2(b)(i) an element contains only one type of atom ; a compound contains two or more elements chemically combined ; 2 2(b)(ii) particles separation particle arrangement particle motion solid close together regular vibrate about a fixed point gas far apart random move rapidly in all directions particle separation column ; particle arrangement column ; 2 2(c)(i) A ; 1 2(c)(ii) B ; 1 2(c)(iii) 2 non-metal atoms bonding / electrons are shared ; 1 (a)(i) To earn this mark, you must write the correct word equation for the thermal decomposition of calcium carbonate, including the arrow and plus signs. (a)(ii) You need to state any one valid use of limestone, such as neutralizing acidic soil, as a building material, or for cement. (a)(iii) To get this mark, you must correctly identify the number of different elements present in the formula CaCO3. (a)(iv) You earn this mark by explaining that new substances are produced during the thermal decomposition. (a)(v) This mark is awarded for stating that an endothermic reaction involves the taking in of thermal energy. (b)(i) You must define an element as containing only one type of atom and a compound as containing two or more elements chemically combined. (b)(ii) You need to correctly fill in the 'particle separation' and 'particle arrangement' columns for both solid and gas, showing close together/regular for solid and far apart/random for gas. (c)(i) You must select option A. (c)(ii) You must select option B. (c)(iii) You need to explain that covalent bonding involves two non-metal atoms bonding or that electrons are shared.

Cambridge IGCSE Co-ordinated Sciences · 0654

IGCSE Co-ordinated Sciences (0654) Chemical reactions past paper questions

Revise IGCSE Co-ordinated Sciences (0654) — Chemical reactions 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.

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

Chemical reactions in IGCSE Co-ordinated Sciences 0654 exams, 2020–2025

Across 2020–2025, Chemical reactions accounted for 299 questions worth 1,729 marks in Cambridge IGCSE Co-ordinated Sciences (0654) papers.

By year
Year	Questions	Marks
2020	43	221
2021	53	253
2022	52	314
2023	48	299
2024	60	352
2025	43	290

Most-tested subtopics

C6.2 Rate of reaction990 marks
C6.1 Physical and chemical changes409 marks
C6.3 Redox296 marks

Appears in

Paper 1 · 68 qs
Paper 2 · 77 qs
Paper 3 · 67 qs
Paper 4 · 53 qs
Paper 5 · 17 qs
Paper 6 · 17 qs

All most-tested Co-ordinated Sciences topics

2021 Feb/Mar · Paper 3 · Q2 · 10 marks
Marking scheme
Get Steven’s plain-English explanation
2021 May/Jun · Paper 3 · Q2 · 13 marks
Marking scheme
Get Steven’s plain-English explanation
2021 May/Jun · Paper 3 · Q2 · 13 marks
Marking scheme
Get Steven’s plain-English explanation
2021 Oct/Nov · Paper 3 · Q2 · 12 marks
Marking scheme
Get Steven’s plain-English explanation
2021 Oct/Nov · Paper 1 · Q14 · 1 mark
Marking scheme
Mark scheme — 2021 Paper 1 Q14
Answer: B
Get Steven’s plain-English explanation