Group I properties — Paper 3 · IGCSE Science - Combined 0653

8 (a) A student observes what happens when a piece of sodium is added to water, as shown in Fig. 8.1. sodium water Fig. 8.1 During the reaction the student observes that the sodium floats and melts. The student is told that sodium hydroxide solution is formed and hydrogen gas is given off. (i) State which information above shows that sodium has a low density. … [1] (ii) Complete the word equation for this reaction. + + [2] (iii) The student makes different observations when a piece of copper is added to water. Describe these different observations. 1. … 2. … [2] (b) The Periodic Table contains groups and collections of elements. (i) Name the collection of metals which often act as catalysts. … [1] (ii) Describe the reactivity of the noble gases. … [1] (iii) Chlorine, Cl, is in Group VII of the Periodic Table. An atom of chlorine is represented as: 3517Cl The mass number is 35, and the atomic number is 17. Explain what is meant by mass number, … … atomic number. … … [2]

9 marks

Mark scheme: 8(a)(i) floats ; 1 8(a)(ii) LHS (either order) ; RHS (either order) ; sodium + water Î sodium hydroxide + hydrogen 2 8(a)(iii) sinks ; no reaction ; either order 2 8(b)(i) transition metals ; 1 8(b)(ii) unreactive ; 1 8(b)(iii) mass no. (35) number of protons + neutrons ; atomic no. (17) number of protons ; 2

This question in 0653/32 Feb/March 2017

2 (a) A teacher places the first three metals of Group I in the Periodic Table into separate beakers of water. This is shown in Fig. 2.1. water beaker A beaker B beaker C Fig. 2.1 The three pieces of metal are the same size. A student records her observations in Table 2.1. Table 2.1 time for metal beaker the metal floats the metal melts to fully react in flames are seen seconds A yes yes 15 yes B yes no 60 no C yes yes 40 no (i) Use the information in Table 2.1 to identify the three metals in beakers A, B and C. beaker A … beaker B … beaker C … [2] (ii) Name the gas produced when Group I metals react with water. … [1] (iii) When the metals have completely reacted, the teacher places pieces of red litmus paper and blue litmus paper into each beaker. Describe the changes, if any, that are seen. red litmus paper … blue litmus paper … [1] (b) The student places pieces of copper, iron, magnesium and zinc into dilute hydrochloric acid. (i) State which of the four metals react fastest. … [1] (ii) State which of the four metals does not react at all. … [1] (iii) Suggest why Group I metals must not be added to dilute hydrochloric acid. … … [1] (c) Saucepans are usually made from an iron alloy rather than from pure iron. Some coins are made from a copper alloy rather than from pure copper. Explain why these alloys are used instead of the pure metals. (i) iron alloy for saucepans … … [1] (ii) copper alloy for coins … … [1]

9 marks

Mark scheme: 2(a)(i) potassium / K lithium / Li sodium / Na ;; 2 2(a)(ii) hydrogen / H2 ; 1 2(a)(iii) turns blue and stays blue / no change ; 1 2(b)(i) magnesium / Mg ; 1 2(b)(ii) copper / Cu ; 1 2(b)(iii) (too) dangerous / (risk of) explosion ; 1 2(c)(i) resists corrosion / does not rust ; 1 2(c)(ii) stronger / does not get damaged ; 1

This question in 0653/32 May/June 2017

2 (a) A teacher places the first three metals of Group I in the Periodic Table into separate beakers of water. This is shown in Fig. 2.1. water beaker A beaker B beaker C Fig. 2.1 The three pieces of metal are the same size. A student records her observations in Table 2.1. Table 2.1 time for metal beaker the metal floats the metal melts to fully react in flames are seen seconds A yes yes 15 yes B yes no 60 no C yes yes 40 no (i) Use the information in Table 2.1 to identify the three metals in beakers A, B and C. beaker A … beaker B … beaker C … [2] (ii) Name the gas produced when Group I metals react with water. … [1] (iii) When the metals have completely reacted, the teacher places pieces of red litmus paper and blue litmus paper into each beaker. Describe the changes, if any, that are seen. red litmus paper … blue litmus paper … [1] (b) The student places pieces of copper, iron, magnesium and zinc into dilute hydrochloric acid. (i) State which of the four metals react fastest. … [1] (ii) State which of the four metals does not react at all. … [1] (iii) Suggest why Group I metals must not be added to dilute hydrochloric acid. … … [1] (c) Saucepans are usually made from an iron alloy rather than from pure iron. Some coins are made from a copper alloy rather than from pure copper. Explain why these alloys are used instead of the pure metals. (i) iron alloy for saucepans … … [1] (ii) copper alloy for coins … … [1]

9 marks

Mark scheme: 2(a)(i) potassium / K lithium / Li sodium / Na ;; 2 2(a)(ii) hydrogen / H2 ; 1 2(a)(iii) turns blue and stays blue / no change ; 1 2(b)(i) magnesium / Mg ; 1 2(b)(ii) copper / Cu ; 1 2(b)(iii) (too) dangerous / (risk of) explosion ; 1 2(c)(i) resists corrosion / does not rust ; 1 2(c)(ii) stronger / does not get damaged ; 1

This question in 0653/33 May/June 2017

2 (a) A teacher puts a small piece of sodium onto water in a water trough, as shown in Fig. 2.1. sodium water water trough Fig. 2.1 The students observe the reaction between sodium and water. The teacher repeats the experiment using potassium instead of sodium. (i) Describe one similarity in the reactions of potassium and of sodium with water. … [1] (ii) Describe one difference between the observations for the reactions of potassium and of sodium with water. Explain the reason for this difference. difference … explanation … [2] (b) Iron is in a collection of metals in the Periodic Table shown on page 20. (i) Name this collection of metals. … [1] (ii) State one physical property of iron that is also a physical property of sodium. … [1] (iii) State one property of iron that is not a property of sodium. … [1] (c) The metals aluminium, copper and iron can be recycled. State one reason, other than cost, why these metals can be recycled. … … [1] (d) An atom of aluminium is represented by the symbol shown. 2 1 37Al (i) Complete Fig. 2.2 to show the electronic structure of this atom. Fig. 2.2 [2] (ii) Describe how this atom forms an aluminium ion, Al 3+. … … [1] [Total: 10]

10 marks

Mark scheme: 2(a)(i) any one from: exothermic / releases heat ; fizzes / releases gas / H2 ; forms an alkaline solution ; max 1 2(a)(ii) (difference) (potassium) burns / produces flames ; (explanation) (potassium is) more reactive (than sodium) ; 2 2(b)(i) transition (elements) ; 1 2(b)(ii) any one from: (good) conductor of electricity ; (good) conductor of heat ; malleable ; 1 Question Answer Marks 2(b)(iii) any one from: high melting point ; high boiling point ; high density ; forms coloured compounds ; (acts as) catalyst (as element or in compounds) ; 1 2(c) (they are) finite resources / (they’re) running out / will run out / more energy used for extraction / less energy to recycle (than extract) / no need to mine / does not go into landfill ; 1 2(d)(i) 2, 8, 3 shown correctly ;; (if incorrect allow 1 mark for 13 electrons drawn) 2 2(d)(ii) loss of electrons ; 1

This question in 0653/32 May/June 2020

5 (a) An iron paperclip, shown in Fig. 5.1, is used to hold pieces of paper together. Fig. 5.1 Iron can be described as a strong metal. Name one other property of iron that makes it suitable for use as a paperclip. … [1] (b) A spanner, shown in Fig. 5.2, is made from an alloy of iron. Fig. 5.2 (i) Describe what is meant by an alloy. … … [1] (ii) Suggest why the spanner is made from an alloy of iron and not from pure iron. … … [1] (c) Lithium, sodium and potassium are Group I metals. Describe the trend in density and the trend in reaction with water of the Group I metals going down the group. density … … reaction with water … … [2] (d) Copper and iron are part of a collection of metals in the Periodic Table. (i) State the name of this collection of metals. … [1] (ii) Copper and iron are less reactive than Group I metals. Copper and iron have high melting points and high densities, but Group I metals do not. State one other property of copper and iron that is not a property of Group I metals. … [1] (e) When sodium reacts with chlorine, sodium chloride is formed. Fig. 5.3 shows the electronic structures of a sodium atom and of a chlorine atom. sodium atom chlorine atom Fig. 5.3 Sodium chloride contains sodium ions and chloride ions. Complete Fig. 5.4 to show the electronic structures of a sodium ion and a chloride ion. sodium ion chloride ion Fig. 5.4 [2] [Total: 9]

9 marks

Mark scheme: 5(a) malleable ; 1 5(b)(i) a mixture of a metal with other element(s) ; 1 5(b)(ii) pure iron is too soft / alloys are stronger / alloys resist, corrosion / rusting ; 1 5(c) (density) increases (down the group) ; (reaction with water) reactivity increases (down the group) ; 2 5(d)(i) transition (elements/metals) ; 1 5(d)(ii) form coloured compounds / (act as) catalysts ; 1 5(e) (sodium ion) 2,8 ; (chloride ion) 2,8,8 ; 2

This question in 0653/32 Feb/March 2021

2 (a) Fig. 2.1 shows part of Group I of the Periodic Table. 3 Li lithium 7 11 Na sodium 23 19 K potassium 39 Fig. 2.1 (i) State the trend in the reactivity of the elements going down Group I. … [1] (ii) Explain why lithium does not react with helium, a Group VIII element. … … [1] (iii) Lithium is a solid and helium is a gas. Describe two differences between the structures of a solid and a gas. 1 … … 2 … … [2] (b) A piece of sodium is added to water, as shown in Fig. 2.2. sodium water Fig. 2.2 The sodium reacts with water. The reaction is exothermic. (i) State one other observation that is seen when sodium reacts with water. … [1] (ii) Complete the word equation for the reaction of sodium with water. sodium + water + [2] (c) X is a compound that reacts with dilute hydrochloric acid to form sodium chloride and water. Suggest the identity of X. … [1] (d) Concentrated aqueous sodium chloride is broken down by electrolysis. (i) State the type of chemical bond in sodium chloride. … [1] (ii) Identify the product that forms at the anode (positive electrode). … [1] [Total: 10]

10 marks

Mark scheme: 2(a)(i) increasing / more reactive / faster reaction ; 1 2(a)(ii) helium / He is, unreactive / inert ; 1 2(a)(iii) any two from: (solid/lithium) particles close(r) (together) ORA ; (solid/lithium) particles regular arrangement ORA ; (solid/lithium) particles vibrate / not free-moving ORA ; 2 Question Answer Marks 2(b)(i) fizzes / bubbles OR gets smaller / disappears OR moves around ; 1 2(b)(ii) sodium + water → sodium hydroxide + hydrogen in either order sodium hydroxide ; hydrogen ; 2 2(c) sodium hydroxide / NaOH OR sodium carbonate / Na2CO3 ; 1 2(d)(i) ionic ; 1 2(d)(ii) chlorine / Cl2 ; 1

This question in 0653/31 May/June 2021

5 (a) A student investigates the reaction between dilute hydrochloric acid and a 5.0 g piece of zinc using the apparatus shown in Fig. 5.1. gas apparatus X dilute hydrochloric acid stopwatch funnel to collect gas zinc Fig. 5.1 The reaction forms a gas and a solution containing a zinc salt. (i) Complete the word equation for this reaction. zinc + hydrochloric acid + [2] (ii) Name apparatus X. … [1] (iii) Describe a chemical test to show that the solution contains zinc ions, Zn2+. test … result … … [2] (iv) The student repeats the experiment under the same conditions, using 5.0 g of magnesium instead of zinc. State the change to the rate of the reaction, if any, that occurs when magnesium is used instead of zinc. Explain your answer. rate change … explanation … … [1] (b) Zinc and other metals are obtained from their ores. They are also obtained by recycling. Recycling metals costs less than obtaining metals from their ores. State one other reason why metals are recycled. … [1] (c) Lithium, sodium and potassium are Group I metals. Describe one chemical trend and one physical trend in the properties of these metals going down Group I from lithium to potassium. chemical trend … … physical trend … … [2] [Total: 9]

9 marks

Mark scheme: 5(a)(i) zinc + hydrochloric acid → zinc chloride + hydrogen zinc chloride ; hydrogen ; 2 5(a)(ii) measuring cylinder ; 1 5(a)(iii) test: aqueous NaOH OR aqueous ammonia ; result: white ppt. (soluble in excess) ; 2 5(a)(iv) rate change: increase / faster AND explanation: magnesium is more reactive (than zinc) ORA ; 1 5(b) ores are a finite resource / will run out ; 1 5(c) chemical trend: more reactive ; physical trend: lower melting point OR higher density ; 2

This question in 0653/32 May/June 2021

2 (a) A student has two samples of pure water in test-tubes A and B, and two samples of impure water in test-tubes C and D. A different substance is added to each test-tube as shown in Fig. 2.1. aqueous white solid aqueous barium ions in copper(II) sulfate cobalt(II) chloride sodium hydroxide acidic solution pure impure water water A B C D Fig. 2.1 (i) State the colours of the solutions formed in test-tubes A and B. A … B … [2] (ii) When aqueous sodium hydroxide is added to impure water in test-tube C, a brown precipitate is formed. Identify the ion in the impure water that causes this change. … [1] (iii) When aqueous barium ions in acidic solution are added to test-tube D, a white precipitate is formed. Identify the ion in the impure water that causes this change. … [1] (b) A teacher adds a small piece of sodium to some water in a beaker, as shown in Fig. 2.2. thermometer piece of sodium water Fig. 2.2 Sodium reacts with the water in an exothermic reaction. An alkaline solution and a colourless gas are made. (i) Describe what happens to the reading on the thermometer. … [1] (ii) Complete the word equation for this reaction. sodium + water + [2] (c) Water molecules contain atoms of two non-metallic elements. (i) State the type of chemical bond in a molecule of water. … [1] (ii) Complete the dot-and-cross diagram in Fig. 2.3 to show all of the outer shell electrons in a molecule of water. H O H Fig. 2.3 [2] [Total: 10]

10 marks

Mark scheme: 2(a)(i) A (turns) blue ; B (turns) pink ; 2 2(a)(ii) iron(III) / Fe3+ ; 1 2(a)(iii) sulfate / SO42– ; 1 2(b)(i) increases / rises ; 1 Question Answer Marks 2(b)(ii) ; IN EITHER ORDER: sodium hydroxide ; hydrogen ; 2 2(c)(i) covalent ; 1 2(c)(ii) two correct O — H electron pairs ; all else correct ; 2

This question in 0653/32 Feb/March 2022

8 (a) Lithium, sodium and potassium are metals in Group I of the Periodic Table. Chlorine, bromine and iodine are halogens in Group VII of the Periodic Table. Helium, neon and argon are elements in Group VIII of the Periodic Table. (i) State the trend in the density of the elements going down Group I. … [1] (ii) State the trend in the colour of the elements going down Group VII. … [1] (iii) Identify one similarity between the elements in Group VIII. … [1] (b) Aluminium, calcium, iron and sodium are in different groups of the Periodic Table. Place these metals in order of reactivity, from most to least reactive. … most reactive … … … least reactive [2] (c) An atom of sodium is represented as shown. 23 11Na Deduce the number of protons and the number of neutrons in this atom. protons … neutrons … [2] (d) State one use of helium. … [1] [Total: 8]

8 marks

Mark scheme: 8(a)(i) increases (down the group) ; 1 8(a)(ii) (they get) darker ; 1 8(a)(iii) unreactive / inert ; 1 Question Answer Marks 8(b) sodium calcium aluminium iron ;; all correct (2) sodium is most reactive (1) 2 8(c) (protons) 11 ; (neutrons) 12 ; 2 8(d) filling balloons ; 1

This question in 0653/31 May/June 2022

5 (a) Lithium, sodium and potassium are three elements in Group I of the Periodic Table, as shown in Fig. 5.1. 3 Li lithium 7 11 Na sodium 23 19 K potassium 39 Fig. 5.1 Identify which of these three elements has: the lowest density … the highest reactivity … the highest melting point. … [2] (b) Chlorine, bromine and iodine are three elements in Group VII of the Periodic Table. They exist as diatomic molecules. (i) Describe what is meant by diatomic. … … [1] (ii) Complete the dot‑and‑cross diagram in Fig. 5.2 to show all the outer shell electrons in a molecule of chlorine, Cl 2. Cl Cl Fig. 5.2 [2] (iii) State the type of chemical bonding in a molecule of chlorine. … [1] (c) When sodium and chlorine react together, they form sodium chloride, NaCl. (i) Describe what happens to sodium atoms and to chlorine atoms when they react together. Use ideas about electrons in your answer. sodium atoms … … chlorine atoms … … [2] (ii) Complete Table 5.1 by stating whether each substance conducts or does not conduct electricity when solid, molten (liquid) or gas. Use a tick (✓) for conducts or a cross (✗) for does not conduct in each empty box. Table 5.1 solid molten (liquid) gas sodium sodium chloride chlorine [3] [Total: 11]

11 marks

Mark scheme: 5(a) (lowest density) lithium / Li (highest reactivity) potassium / K (highest melting point) lithium / Li Three correct scores (2) ;; Two or one correct scores (1) ; 2 5(b)(i) contains only two atoms (per molecule) ; 1 5(b)(ii) correct diagram showing two shared electrons ; and 6 non-shared (3 pairs of) electrons on each chlorine ; 2 5(b)(iii) covalent ; 1 5(c)(i) (sodium atoms) lose electrons / lose one electron each ; (chlorine atoms) gain electrons / gain one electron each ; 2 5(c)(ii) ;;; (1) for each correct row 3

This question in 0653/33 May/June 2022

8 The Periodic Table contains groups and collections of different elements. (a) Fig. 8.1 lists some of the elements in Group I. 3 Li lithium 7 11 Na sodium 23 19 K potassium 39 Fig. 8.1 The elements in Group I react with water to produce a gas. (i) State the name of this gas. … [1] (ii) State the trend in the reactivity of the elements down Group I. … [1] (b) Fig. 8.2 lists some of the elements in Group VII. 17 Cl chlorine 35.5 35 Br bromine 80 53 I iodine 127 Fig. 8.2 The elements in Group VII exist as diatomic molecules. (i) State what is meant by diatomic. … [1] (ii) State the trend in the colour of the elements down Group VII. … [1] (c) Iron and copper are part of a collection of metals which have high densities. (i) State the name of this collection of metals. … [1] (ii) Iron and copper and their compounds act as catalysts. State one other property of these metals that is not a property of Group I metals. … [1] (d) Argon and helium are noble gases. Argon is used in lamps, and helium is used in balloons, as shown in Fig. 8.3. argon helium Fig. 8.3 Identify one property of each element that makes it suitable for the use shown in Fig. 8.3. argon … helium … [2] [Total: 8]

8 marks

Mark scheme: 8(a)(i) hydrogen ; 1 8(a)(ii) increases (going down) ; 1 8(b)(i) contains two atoms (chemically) joined or bonded / a molecule containing two atoms ; 1 8(b)(ii) (become) darker / deeper ; 1 8(c)(i) transition (elements / metals) ; 1 8(c)(ii) high melting points / form coloured compounds ; 1 8(d) (argon) unreactive ; (helium) low density ; 2

This question in 0653/33 May/June 2023

5 Part of the Periodic Table is shown in Fig. 5.1. Group I II III IV V VI VII VIII H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Fig. 5.1 (a) (i) Draw one straight line to show the trend in metallic character across a period. decreases across a period from left to right metallic increases across a period character from left to right stays the same across a period from left to right [1] (ii) State the name of the collection of metals that includes iron, Fe, and copper, Cu. … [1] (b) Lithium, Li, sodium, Na, and potassium, K, are in Group I of the Periodic Table. State the trend in the melting point and the trend in the reaction with water of these elements going down Group I. melting point … … reaction with water … … [2] (c) Sodium, Na, reacts with fluorine, F, to form sodium fluoride. Fig. 5.2 shows the electronic structure of a sodium atom and of a fluorine atom. sodium atom fluorine atom Fig. 5.2 When sodium atoms react with fluorine atoms, sodium ions and fluoride ions form. Complete the dot-and-cross diagrams in Fig. 5.3 to show all of the electrons in a sodium ion and in a fluoride ion. sodium ion fluoride ion Fig. 5.3 [2] (d) The electronic structure of an atom of element Z is shown in Fig. 5.4. element Z Fig. 5.4 (i) Use the Periodic Table to identify element Z. … [1] (ii) Sodium and element Z do not easily form a compound together. Use the electronic structure shown in Fig. 5.4 to explain this observation. … … … [2] [Total: 9]

9 marks

Mark scheme: 5(a)(i) metallic character - decreases across a period from left to right ; 1 5(a)(ii) transition (elements) ; 1 5(b) (melting point) decreases (down Group I) ; (reaction with water) more reactive / reacts more vigorously / reacts faster (down Group I) ; 2 5(c) (sodium ion) 2 electrons in 1st shell, 8 in 2nd shell only (no electrons in 3rd shell) ; (fluoride ion) 2 electrons in 1st shell, 8 in 2nd shell only ; 2 5(d)(i) argon ; 1 5(d)(ii) Z has full outer shell / 8 electrons in outer shell ; Z does not need to gain an electron (from sodium) / Z has a stable electron arrangement ; 2

This question in 0653/33 May/June 2024

4 Lithium, sodium and potassium are elements in Group I of the Periodic Table. (a) Melting point and boiling point are properties of the elements in Group I. These properties show a trend down Group I. State two other properties that show a trend down Group I. 1 … 2 … [2] (b) A mixture of sodium and potassium is used as a coolant in nuclear reactors. (i) Circle the word that describes a mixture of metals. alloy brass compound element [1] (ii) The melting point and boiling point of a mixture of sodium and potassium are shown in Table 4.1. Table 4.1 melting point boiling point / °C / °C mixture of sodium and potassium –13 785 Room temperature is 25 °C. Deduce whether the mixture of sodium and potassium is a solid, a liquid or a gas at room temperature. Use Table 4.1 to explain your answer. solid, liquid or gas … explanation … … [2] (c) The arrangement of particles in an atom of lithium is shown in Fig. 4.1. – – + + + – Fig. 4.1 Complete the labels in Fig. 4.1 with the name of each particle in the atom. [3] [Total: 8]

8 marks

Mark scheme: 4(a) density ; 2 reactivity with water ; 4(b)(i) alloy ; 1 more than one answer circled = 0 marks 4(b)(ii) liquid ; 2 melting point is below room temperature and / or boiling point is above room temperature / owtte ; 4(c) electron ; 3 neutron ; proton ;

This question in 0653/32 Feb/March 2025

5 Potassium and magnesium are metals. (a) A solid compound contains potassium ions. Describe the use of a flame test to identify potassium ions. … … … … [2] (b) A small piece of potassium is added to cold water. An exothermic reaction happens. (i) Complete the sentence about an exothermic reaction. An exothermic reaction transfers … energy to the surroundings. [1] (ii) State one observation that shows this reaction is exothermic. … [1] (iii) Complete the word equation for this reaction. potassium + water + [1] (c) Magnox is an alloy of magnesium. Describe what is meant by an alloy. … … [1] (d) The proton number of magnesium is 12. Determine the electronic configuration of magnesium. … [1] (e) Fig. 5.1 shows the structure of a compound of magnesium. Br H Mg H H C C C C H H H H Fig. 5.1 Deduce the molecular formula of this compound. … [1] [Total: 8]

8 marks

Mark scheme: 5(a) any two from: 2 dip (nichrome) wire or splint in potassium compound ; at (edge of) a blue Bunsen flame ; lilac flame observed ; 5(b)(i) thermal ; 1 5(b)(ii) a flame (is observed) ; 1 5(b)(iii) potassium hydroxide and hydrogen ; 1 5(c) mixture of a metal and other element(s) ; 1 5(d) 2,8,2 ; 1 5(e) C4H7MgBr ; 1

This question in 0653/31 May/June 2025

4 (a) Solid sodium reacts with water. (i) Circle the gas that forms when sodium reacts with water. carbon dioxide chlorine hydrogen oxygen [1] (ii) State one way the reaction of potassium with water is different from the reaction of sodium with water. … … [1] (b) Aqueous sodium chloride is a mixture of two compounds, sodium chloride and water. State one similarity and one difference between a compound and a mixture. similarity … … difference … … [2] (c) Solid sodium is heated to form a liquid. (i) Tick () all the boxes that show correct properties of a liquid. A liquid cannot be squashed. A liquid has no fixed volume. A liquid takes the shape of its container. [1] (ii) The symbol for solid sodium is Na(s). Complete the symbol for liquid sodium by adding the missing state symbol. Na( … ) [1] (d) The noble gases are in Group VIII of the Periodic Table. Explain how the electronic configuration of neon affects its reactivity. … … [1] (e) Nitrogen is a gas. (i) State the percentage of nitrogen gas in clean, dry air. … % [1] (ii) Oxides of nitrogen are air pollutants. State one source of these oxides of nitrogen. … [1] (iii) State one adverse effect of oxides of nitrogen. … [1] [Total: 10]

10 marks

Mark scheme: 4(a)(i) hydrogen ; 1 4(a)(ii) any one from: 1 idea of potassium is more reactive than sodium ; (potassium) moves more quickly on surface of water / ignites ; 4(b) similarity: 2 both contain two or more different, atoms / elements ; any one difference: in a compound, (the atoms / ions / elements) are (chemically) bonded together ORA ; a compound cannot be changed back / separated (into its elements) (by physical means) / mixture can be separated (by physical means) ; 4(c)(i) first and last box ticked ; 1 4(c)(ii) l / l ; 1 4(d) full outer shell or 2,8 and unreactive / inert / stable ; 1 4(e)(i) 78(%) ; 1 4(e)(ii) (reactions in) car engines ; 1 4(e)(iii) any one from: 1 acid rain ; respiratory problems ;

This question in 0653/32 May/June 2025

6 (a) Fig. 6.1 shows Group I of the Periodic Table. 3 Li lithium 7 11 Na sodium 23 19 K potassium 39 37 Rb rubidium 85 55 Cs caesium 133 87 Fr francium – Fig. 6.1 (i) Write a number in each gap to complete the sentence. An atom of potassium contains … protons and … neutrons. [2] (ii) The electronic configuration of a potassium atom is 2,8,8,1. State two ways that the electronic configuration is related to the position of potassium in the Periodic Table. 1 … … 2 … … [2] (iii) Complete Table 6.1 with information about an electron. Table 6.1 relative charge relative mass proton +1 1 electron [2] (b) Fig. 6.2 shows the reaction of potassium with water. thermometer flame bubbles potassium water containing universal indicator Fig. 6.2 (i) State the flame test colour for potassium. … [1] (ii) A gas is produced during the reaction. Describe a test to identify the gas. Give the observation for a positive result. test … observation … [2] (iii) The temperature of the water increases during the reaction. Name the type of reaction that causes an increase in the temperature of the surroundings. … [1] (iv) The universal indicator turns purple during the reaction. Suggest the pH of the solution formed during the reaction. pH = … [1] [Total: 11]

11 marks

Mark scheme: 6(a)(i) 19 ; 2 20 ; 6(a)(ii) potassium is in the fourth period / row because it has 4 shells ; 2 potassium has 1 electron in its outer shell so that makes it group 1 ; 6(a)(iii) relative charge: –1 ; 2 relative mass: 1 / 1835 ; 6(b)(i) lilac ; 1 6(b)(ii) lighted splint ; 2 pops ; 6(b)(iii) exothermic ; 1 6(b)(iv) answer within range 10–14 ; 1

This question in 0653/32 Oct/Nov 2025

6 (a) Fig. 6.1 shows Group I of the Periodic Table. 3 Li lithium 7 11 Na sodium 23 19 K potassium 39 37 Rb rubidium 85 55 Cs caesium 133 87 Fr francium – Fig. 6.1 (i) Write a number in each gap to complete the sentence. An atom of potassium contains … protons and … neutrons. [2] (ii) The electronic configuration of a potassium atom is 2,8,8,1. State two ways that the electronic configuration is related to the position of potassium in the Periodic Table. 1 … … 2 … … [2] (iii) Complete Table 6.1 with information about an electron. Table 6.1 relative charge relative mass proton +1 1 electron [2] (b) Fig. 6.2 shows the reaction of potassium with water. thermometer flame bubbles potassium water containing universal indicator Fig. 6.2 (i) State the flame test colour for potassium. … [1] (ii) A gas is produced during the reaction. Describe a test to identify the gas. Give the observation for a positive result. test … observation … [2] (iii) The temperature of the water increases during the reaction. Name the type of reaction that causes an increase in the temperature of the surroundings. … [1] (iv) The universal indicator turns purple during the reaction. Suggest the pH of the solution formed during the reaction. pH = … [1] [Total: 11]

11 marks

Mark scheme: 6(a)(i) 19 ; 2 20 ; 6(a)(ii) potassium is in the fourth period / row because it has 4 shells ; 2 potassium has 1 electron in its outer shell so that makes it group 1 ; 6(a)(iii) relative charge: –1 ; 2 relative mass: 1 / 1835 ; 6(b)(i) lilac ; 1 6(b)(ii) lighted splint ; 2 pops ; 6(b)(iii) exothermic ; 1 6(b)(iv) answer within range 10–14 ; 1

This question in 0653/33 Oct/Nov 2025