Answers to Revision Questions - hodderplus.com to Revision Questions 1 Elements, Mixtures and Compounds 1 a) A substance that consists of only one type of atom [1] ... Al 2 (SO 4)

1CCEA GCSE Chemistry

Answers to Revision Questions

1 Elements, Mixtures and Compounds 1 a) A substance that consists of only one type of atom [1]

b) The simplest particle of an element that can exist on its own in a stable environment [1]

c) Contains two or more elements chemically combined [1]

2 Filtration [1]; through filter paper [1]; sand is the residue [1]; water is the filtrate [1]

3 a) Separating funnel [1]; b) Magnetism [1]

4 Expensive/lack of sensitivity/trained staff required to operate it [1]

5 Small sample/identification of unknown elements or compounds [1]

6 a) Solid that dissolves [1]

b) Liquid in which the solute dissolves [1]

c) Mixture of solute dissolved in the solvent [1]

7 a) 3 [1]; b) water [1]; c) 2 [1]; d) 1 and 4 [1]; e) 1 [1]

f) Does not dissolve in the solvent [1]; g) Solvent front [1]

8 a) Retention time [1]; b) 2 [1]

9 a) B = filter paper [1]; C = filter funnel [1]; D = conical flask [1]

b) Residue [1]; c) Filtrate [1]; d) Sand mixed with water [1]

10 Any two from: malleable/ductile/sonorous/high melting point/good conductor of electricity or heat [2]

11 Fractional distillation [1]

12 Oil and water [1]

13 Mass spectrometry [1]

14 2 [1]

15 (10 × 20) + (11 × 80)(20 + 80)

[1] = 1080100 = 10.8 [1]

2 Atomic Structure and Bonding 1 Number of protons [1]

2 a) 1, +1 [1]; b) 1 1840

, −1 [1]; c) 1, 0 [1]

3 Atoms of the same element with the same number of protons [1]; but different numbers of neutrons [1]

4 Diagrams to match electronic configurations: a) 2,8,5 [1]; b) 2,1 [1]; c) 2,6 [1]; d) 2,8,8,1 [1]; e) 2,8,8 [1]; f) 2 [1]; g) 2,8,3 [1]; h) 2,8,1 [1]

5 a) 2,8 [1]; b) 2,8 [1]; c) 2,8 [1]; d) 2,8 [1]; e) 2,8,8 [1]

6 When molten the ions [1]; can move [1]; and carry charge [1]

7 Sharing of electrons [1]; idea of a pair of electrons shared [1]

8 a) 2 electrons shared in bond [1]

7 electrons in outer shell of each Cl [1]

b) 2 electrons shared in each bond [1]

6 electrons in outer shell of O [1]

1 electron in outer shell of H [1]

Chemistry.indb 1 27/03/12 10:24 AM

2 Answers to Revision Questions

c) 4 electrons shared in each double bond [1]

4 electrons in outer shell of carbon atom [1]

6 electrons in outer shell of both oxygen atoms [1]

9 Little energy required [1]; to break the weak van der Waals’ forces [1]; between chlorine molecules [1]

10 Each carbon atom [1]; covalently [1] bonded; to 4 [1];

other carbon atoms in a tetrahedral structure [1] Max. 3

11 Delocalised electrons [1]; can move [1]; and carry charge [1]

12 Can be hammered into shape [1]

13 Layers [1]; of positive centres/ions [1]; held together by a sea of delocalised electrons [1]

14 20 protons and 20 neutrons [1]; in the nucleus [1]; 20 electrons [1]; arranged 2,8,8,2 [1]

15

ParticleAtomic number

Mass number Protons Neutrons Electrons

Electronic confi guration

X 11 23 11 12 10 2,8 [1]

Y 17 35 17 18 17 2,8,7 [1]

Z 8 16 8 8 10 2,8 [1]

3 Formulae and Equations 1 a) NaF [1]; b) MgO [1]; c) K2O [1]; d) BaCl2 [1]

2 a) CuCl2 [1]; b) ZnO [1]; d) CuSO4 [1]; d) Fe(OH)3 [1]

3 a) Na2CO3 [1]; b) NaHCO3 [1]

4 a) Carbon dioxide [1]; b) Potassium nitrate [1]; c) Copper(II) carbonate (accept copper carbonate) [1]; d) Hydrogen fluoride [1]; e) Magnesium sulfate [1]

5 a) (NH4)2SO4 [1]; b) SO2 [1]; c) Ca(HCO3)2 [1]; d) Al2(SO4)3 [1]

6 S2O32− [1]

7 a) hydroxide [1]; b) oxide [1]; c) chloride [1]; d) aluminium [1]; e) sulfate [1]

8 a) 2KOH + H2SO4 → K2SO4 + 2H2O [3]

b) 2Ca + O2 → 2CaO [3]

c) 2Al + 3Cl2 → 2AlCl3 [3]

9 CuCO3 → CuO + CO2 [2]

10 2C2H6 + 7O2 → 4CO2 + 6H2O [3]; (accept: C2H6 + 312O2 → 2CO2 + 3H2O)

11 a) BaCl2 + K2SO4 → BaSO4 + 2KCl [3]

b) Ba2+ + SO42− → BaSO4 [2]

12 a) Ca(OH)2 + 2HCl → CaCl2 + 2H2O [3]

b) Al2O3 + 3H2SO4 → Al2(SO4)3 + 3H2O [3]

c) Zn + 2HCl → ZnCl2 + H2 [3]

13 N2 + 3H2 → 2NH3 [3]

14 Zn2+ + 2OH− → Zn(OH)2 [3]



15 a) Mg + Cu2+ → Mg2+ + Cu [2]

b) Zn + 2H+ → Zn2+ + H2 [3]

c) CO32− + 2H+ → CO2 + H2O [3]

4 The Periodic Table 1 a) Alkali metals [1]; b) Alkaline earth metals [1]; c) Halogens [1];

d) Noble gases [1]

2 Li → Li+ + e− [2]

3 Phosphorus; P [1]

4 John Newlands [1]

5 a) Pale yellow gas [1]; b) Yellow-green gas [1]; c) Red-brown liquid [1]

d) Grey solid [1]; e) Colourless gas [1]

6 a) Rb+ [1]; b) I− [1]; c) K+ [1]; d) F− [1]

7 Group 6 [1]

8 a) nitrogen [1]; oxygen [1]; fluorine [1]; bromine [1]

b) carbon/sulfur [1]; c) sodium [1]; d) iron [1];

e) oxygen [1]; nitrogen [1]; fluorine [1]

9 Goes dull [1]

10 Fluorine [1]

11 Atomic number [1]

12 Cl2 + 2e− → 2Cl− [3]

13 Any three from: large trough of water/small piece of sodium/safety screen/gloves/glasses/tongs to handle sodium [3]

14 a) 2Na + F2 → 2NaF [3]

b) 2Na + 2H2O → 2NaOH + H2 [3]

15 Any two from: no noble gases/no block of transition metals/no atomic number/fewer elements (gaps)/no actinides or lanthanides [2]

5 Quantitative Chemistry 1 Carbon [1], 12 [1]

2 a) 98 [1]; b) 74 [1]; c) 342 [1]; d) 138 [1]; e) 162.5 [1]

3 a) 281 [1]; b) 238 [1]

4 RFM CaCO3 = 100 [1]; moles CaCO3 = 0.05 [1]; moles CaO = 0.05; [1] RFM CaO = 56 [1]; mass CaO = 2.8 g [1]

5 RFM Mg = 24 [1]; moles Mg = 0.05 [1]; moles MgO = 0.05 [1]; RFM MgO = 40 [1]; mass MgO = 2 g [1]

6 RFM Al = 27 [1]; moles Al = 2000 [1]; moles of Fe2O3 = 1000 [1]; RFM Fe2O3 = 160 [1]; mass of Fe2O3 = 160 kg [1]

7 Moles of Al = 2000 [1]; moles of Fe = 2000 [1]; mass of Fe = 2000 × 56 = 112 kg [1]

8 Moles of Fe = 1.293 [1]; moles of O = 1.725 [1]; simplest ratio = 3 : 4 [1]; so Fe3O4

9 a) RFM CuCl2·2H2O3 = 171 [1]; total RFM water = 36 [1];

% water = 36171

× 100 = 21.05% [1]



b) RFM Na2CO3·10H2O = 286 [1]; total RFM water = 180 [1];

% water = 180286

× 100 = 62.94% [1]

10 Mass of copper = 3.2 g; moles of copper = 0.05 [1]

Mass of oxygen = 0.8 g [1]; moles of oxygen = 0.05 [1];

Simplest ratio = 1 : 1; so CuO [1]

11 H2O2

12 CH2O

13 a) RFM P = 31 [1]; moles P = 0.05 [1]; moles of PCl5 formed = 0.05 [1]

RFM PCl5 = 208.5 [1]; mass PCl5 (theoretical yield) = 10.425 g [1]

b) 8.3410.425

× 100 [1]; = 80% [1]

c) Any one of: side reactions/not all phosphorus reacts/incorrect mass measurements [1]

14 Moles of S = 1.25 [1]; moles of O = 3.75 [1]; simplest ratio = 1 : 3; so SO3 [1]

15 a) 0.212 g [2]; b) 0.002 moles [2]; c) 0.288 g [2]; d) 0.016 moles [2]; e) 8 [2]

6 Acids, Bases and Salts 1 A soluble [1] base [1]

2 Any two from: copper oxide/copper carbonate/copper hydroxide [2]

3 ● Pipette [1];

● a measured volume/25 cm3 of sodium hydroxide solution into a conical flask [1];

● add 5 drops of phenolphthalein [1]; changes to pink [1];

● add sulfuric acid from a burette [1];

● until the indicator changes to colourless [1];

● repeat without the indicator [1];

● heat to reduce the volume by half [1];

● leave aside to cool and crystallise [1];

● filter off the crystals [1];

● dry between two sheets of filter paper/in a low temperature oven/in a desiccator [1];

● in a logical sequence [1] Max. 8

4 a) Purple/dark blue [1]; 12–14 [1]; b) Red [1]; 0–2 [1]; c) Blue [1]; 9–11; d) Yellow or orange [1]; 3–6 [1]; e) Green [1]; 7 [1]

5 H+

6 Any insoluble metal oxide: such as magnesium oxide [1]; copper(II) oxide [1] or any soluble metal hydroxide: such as any Group 1 hydroxide [1] or Group 2 hydroxide [1] Max. 2

7 a) Toxic [1]; fume cupboard [1]; b) Flammable [1]; no naked flames/do not heat [1]; c) Corrosive [1]; wear gloves/personal protective equipment [1]

8 H+(aq) + OH−(aq) → H2O(l) [3]

9 a) Colourless [1]; b) Colourless [1]; c) Pink [1]



10 a) Mg + 2HCl → MgCl2 + H2 [1]

b) Mg(OH)2 + 2HCl → MgCl2 + 2H2O [1]

c) CaCO3 + 2HCl → CaCl2 + CO2 + H2O [1]

11 a) Heat released [1]; bubbles of gas [1]; solid disappears [1]; colourless solution [1] Max. 3

b) Bubbles of gas [1]; green solid disappears [1]; solution changes from colourless to blue [1]

12 sodium chloride [1]

13 a) red [1]; b) red [1]; c) orange [1]; d) colourless [1]

14 hydrogen [1]; hold a lit splint at the mouth of a tube of it [1]; pop sound if hydrogen present [1]

15 a) Residue [1]; b) Filtrate [1];

c) Filter [1] to remove crystals and dry between two sheets of filter paper or in a desiccator or in a low temperature oven [1]

d) Labelled diagram of filter funnel in conical flask [1]; filter paper [1]; residue and filtrate correctly labelled [1]

7 Test for Ions 1 A yellow [1] precipitate [1]

2 Nichrome wire or flame test rod [1]; Clean using deionised water or concentrated hydrochloric acid and heat in non-luminous Bunsen flame [1]; Place in sample and heat sample in non-luminous Bunsen flame [1]; Observe golden yellow flame colour [1] for sodium ions

3 a) iron(III) hydroxide [1]; b) barium sulfate [1]; c) zinc hydroxide [1]

4 a) 3NaOH + FeCl3 → Fe(OH)3 + 3NaCl [3]

b) BaCl2 + MgSO4 → BaSO4 + MgCl2 [2]

c) 2NaOH + Zn(NO3)2 → Zn(OH)2 + 2NaNO3 [3]

5 a) Fe3+ + 3OH− → Fe(OH)3 [3]

b) Ba2+ + SO42− → BaSO4 [2]

c) Zn2+ + 2OH− → Zn(OH)2 [3]

6 a) Red-brown ppt [1]; b) White ppt [1]; c) White ppt [1]

7 a) Mg2+ [1]; b) I− [1]; c) Magnesium iodide [1]

8 Ag+ + Cl− → AgCl [2]

9 Iron(II)/Fe2+ [1]

10 Solid [1]; that may form on mixing two solutions [1]

8 Solubility 1 Decreases [1]

2 a) Liquid [1] in which a solid dissolves [1];

b) Solid [1] that dissolves in the solvent [1];

c) Mixture [1] of solid dissolved in a solvent [1];

d) Maximum amount of solute has dissolved [1] in the solvent at a particular temperature [1]

3 Contains water [1] that is chemically bonded into the crystal structure [1]



4 Units are g/100 g water [1]

5 a) 34.7 (allow 34–35) [1] g/100 g water

b) Yes [1]; solubility at 20 °C = 33 g/100 g; water so 16.5 g required to saturate 50 g of water [1]

c) Solubility at 33 °C = 37 [1] g/100 g water; mass required to saturate 200 g of water = 37 × 2 = 74 [1] g

d) Solubility at 43 °C = 40 [1] g/100 g water; solubility at 23 °C = 34 [1] g/100 g water

Difference in solubility = 40 − 34 = 6 [1] g per 50 g of water = 62

= 3 [1] g

6 Mass of solute [1] that saturates [1] 100 g of water [1] at a particular temperature [1]

7 9.1 × 10020

[1] = 45.5 [1] g/100 g water

8 Oxygen gas solubility decreases [1]; at increased temperature [1]; fish die from lack of oxygen [1]

9 magnesium oxide [1]; barium sulfate [1]

10 25 × 300100

= 75 [1] g

11 0.14 × 10 = 1.4 g needed to saturate 1 kg of water [1]; mass remaining = 2.0 − 1.4 = 0.6 [1] g

12 4.8 × 1005

= 96 [1] g/100 g water

9 Reactivity Series of Metals 1 Hydrogen [1]

2 Any four of: floats/moves about the surface/fizzes/lilac flame/eventually disappears/explodes/heat released [4]

3 2K + 2H2O → 2KOH + H2 [3]

4 Any three from: solid appears/blue solution/fades to green or colourless/heat released [3]

5 By heating [1] damp mineral wool [1]

6 a) Cu + 2AgNO3 → Cu(NO3)2 + 2Ag [3]

b) Nitrate ion/NO3− [1]

c) Cu + 2Ag+ → Cu2+ + 2Ag [3]

7 Aluminium has a protective [1] oxide [1] layer [1]

8 A grey [1] solid [1] burns with a bright white flame [1], forming a white [1] solid [1] Max. 4

9 a) Black [1]; b) Blue [1]; c) Grey [1]

10 a) calcium [1]; b) calcium [1]; c) calcium, aluminium, zinc, copper [1]

11 2Ca + O2 → 2CaO [3]

12 magnesium, manganese, chromium, nickel [1]

13 2Cr + 3Ni(NO3)2 → 2Cr(NO3)3 + 3Ni [3]

14 Mg + Mn2+ → Mg2+ + Mn [2]

15 All nitrates are soluble in water [1]



10 Water 1 Water that does not lather readily [1]; with soap [1]

2 Calcium hydrogen carbonate

3 Hydrated [1] sodium carbonate [1]

4 Advantage: tastes better/better for brewing beer/better for tanning leather [1]

Disadvantage: wastes soap/causes limescale/less efficient kettles [1]

5 White solid [1] forms a colourless solution [1]

6 A substance that absorbs moisture from the air [1]

7 a) Blue [1]; b) Pink [1]

8 a) Limestone [1] reacts [1] with rainwater [1] containing carbon dioxide [1] to form calcium hydrogen carbonate solution [1] Max. 4

b) Carbonate ions/CO32− in hard water [1] react [1] with calcium

ions/Ca2+ from washing soda [1] to form insoluble [1] calcium carbonate/CaCO3 [1] Max. 4

9 For: prevents tooth decay [1]

Against: mass medication/unknown health risks [1]

10 a) 1 [1]; b) 3 [1]; c) 2 [1]; d) All hardness removed [1]; by boiling [1]

11 Different Types of Chemical Reactions 1 a) Gives out heat [1]; b) Takes in heat [1]

2 a) Endothermic [1]; b) Exothermic [1]; c) Endothermic [1]

3 Wegener [1]

4 Magnesium/zinc [1]

5 a) Fuel reacting with oxygen [1] forming oxides [1]; releasing heat [1]

b) Hydrated [1] iron(III) oxide [1]

c) Oxidation and reduction occurring simultaneously in the same reaction [1]

6 a) CuCO3 → CuO + CO2 [2]; b) Green [1] to black [1]; c) Thermal [1] decomposition [1]

7 a) Zn → Zn2+ + 2e− [2]; b) Cu2+ + 2e− → Cu [2]; c) Zn equation [1]

8 Sodium carbonate/potassium carbonate [1]

9 Nitrogen gains hydrogen [1]; gain of hydrogen is reduction [1]

10 Yellow solid [1]; melts/dark red liquid [1]; blue flame [1]; colourless/misty gas [1]; pungent/choking smell [1] Max. 3

11 Air/oxygen [1]; water/moisture [1]

12 2Pb(NO3)2 → 2PbO + 4NO2 + O2 [3]

13 Fossil record is similar in different continents [1]; shape of the continents suggests they fit together [1]; existence of similar animals that could never have lived in water [1]

14 a) Hydrogen [1]; b) Oxygen [1]; c) Nitrogen [1]

15 Magnesium is more reactive than iron [1]; magnesium reacts first before the iron [1]



12 Rates of Reactions 1 Manganese(IV) oxide [1]

2 Any two of: less energy used/fewer steps/renewable raw materials used [2]

3 Gas syringe [1]

4 Iron [1]

5 Rate increases [1]

6 Substance that speeds up [1]; the rate of a chemical reaction [1]; without being used up [1]

7 Hydrogen [1]

8 Size of solid particles/presence of a catalyst [1]

9 Loss of mass [1]; using a conical flask on a balance[1]; or change of volume [1]; in a gas syringe [1]

10 Hydrogen ions/particles move faster/have more energy [1]; so there are more collisions [1]; and more successful collisions/more collisions with higher than activation energy [1]; in a given period of time [1]; rate increases [1] Max. 4

11 a) 80 seconds [1]; b) 80 cm3 [1]; c) 25 seconds [1];

d) Starts at 0 [1]; remains higher [1]; levels off at same level [1]

e) Starts at 0 [1]; remains lower [1]; levels off at same level [1]

13 Non-metals 1 a) Manganese dioxide [1]; hydrogen peroxide [1]

b) Calcium carbonate [1]; hydrochloric/nitric acid [1]

c) Zinc/magnesium [1]; hydrochloric/sulfuric acid [1]

d) Any ammonium salt [1]; sodium hydroxide/any Group 1 or 2 metal hydroxide [1]

2 a) Pops [1]; with a lighted splint [1]

b) Changes limewater [1]; from colourless [1]; to milky [1]

c) Relights [1]; a glowing splint [1]

d) Glass rod [1]; dipped in concentrated hydrochloric acid [1]; held near gas [1]; produces white smoke [1]

3 NH3 + H2O → NH4OH [2]; hydroxide ions make the solution alkaline [1]

4 Any two of: fire extinguishers/carbonated drinks/dry ice [2]

5 Blue [1] solution; blue [1] precipitate forms [1]; this redissolves [1]; forming a dark blue solution [1] Max. 4

6 a) Sulfur [1]; air [1]; b) Vanadium(V) oxide/vanadium pentoxide/V2O5 [1]; c) 450 °C [1]

7 Contact process [1]

8 Wear gloves/glasses/lab coat [1]; add acid to water [1]; slowly/dropwise [1]; with stirring [1] Max. 3

9 Blue [1] solid turns to a white [1] solid

10 a) S + O2 → SO2 [2]; b) Yellow solid melts/forms a red liquid [1]; pungent/colourless [1] gas [1] formed



11 a) 2Mg + CO2 → 2MgO + C [3]; b) A bright white light [1]; forming a white solid [1]; and black specs [1]

12 N2 + 3H2 ⇌ 2NH3 [3]

13 bubbles of gas/solid disappears/colourless solution [3]

14 Different forms/structures of the same element [1]; in the same physical state [1]

15 Rhombic [1]; monoclinic [1]; plastic [1]

14 Organic Chemistry 1 a) C2H6 [1]; b) C2H4 [1]; c) C4H10 [1]; d) CH4 [1]

2 Red-brown [1] solution; changes to colourless [1]

3 A compound [1] containing only carbon and hydrogen [1]

4 a) Propane [1]; b) ethanol [1]; c) ethene [1]

5 C2H5OH + 3O2 → 2CO2 + 3H2O [3]

6 Ethanol [1]

7 Fractional [1] distillation [1]

8 It turns from orange [1]; to green [1]

9 2CH3COOH + Mg → (CH3COO)2Mg + H2 [3]

10 Family of organic compounds with the same general formula [1]; that differ by a CH2 unit [1]; and show a gradation in their physical properties [1]; and similar chemical properties [1] Max.3

11 a) Polythene [1]; b) Polyvinyl chloride/PVC [1]

12 Climate change [1]; increased sea levels [1]; melting of polar ice caps [1]

13 Carbon monoxide/soot [1]; water [1]

14 Formed from dead plants and animals [1]; over millions of years [1]; under the action of pressure and heat [1]

15 CnH2n+2

15 Quantitative Chemistry 1 48

(48 + 10) ×100 [1] = 82.8 [1] %

2 CCl4 is 92.2 %, HCl is 97.3 %, PCl5 is 85.2 % [1]; so HCl [1]

3 Rinse with deionised water [1]; rinse with the solution being used in the burette [1]; fill with the solution ensuring no air bubbles/jet is filled [1]; read the volume from the bottom of the meniscus [1] Max. 3

4 Yellow [1]; to red/orange [1] Note: 1 mark awarded if the colour change is the wrong way round

5 0.624

[1] = 0.025 [1] moles Mg

Moles H2SO4 = 0.025 [1]; volume of H2SO4 = 0.0252

× 1000 = 12.5 [1] cm3

6 Moles Al = 227

[1] = 0.0741 [1]; so moles Al2O3 = 0.037 [1]

Mass of Al2O3 = 0.037 × 102 [1] = 3.78 [1] g

7 Rinse with deionised water [1]; rinse with the solution being used in the pipette [1]; using a pipette filler [1]; draw up the solution until the bottom of the meniscus is on the line [1]; release into a conical flask and touch the tip of the pipette on the surface of the solution [1] Max. 4



8 a) 19.5 × 0.251000

[1]; = 0.004875 [1]

b) Ratio KOH : H2SO4 is 2 : 1 so moles KOH = 0.004875 × 2 = 0.00975 [1]

c) Concentration of KOH = 0.00975 × 1000

25 [1] = 0.39 [1] mol/dm3

9 a) 17.5 × 0.21000

[1] = 0.0035 [1]

b) 1 : 1 ratio, so moles of MOH = 0.0035 [1]

c) In 100 cm3 [1]; so moles MOH = 0.0035 × 4 = 0.014 [1]

d) RFM = 0.560.014

[1] = 40 [1]

e) RAM = 40 – 16 − 1 [1] = 23 [1]

f) Sodium/Na [1]

10 a) 20.7 × 0.051000

[1] = 0.001035 [1]

b) 1 : 1 ratio, so moles KOH = 0.001035 [1]

c) 0.001035 × 100025

[1] = 0.0414 [1] mol/dm3

d) Dilution factor = 25010 = 25 [1]; so concentration = 0.0414 × 25 =

1.035 [1] mol/dm3

e) RFM of KOH = 56 [1] so concentration = 1.035 × 56 = 57.96 [1] g/dm3

16 Materials 1 Any three of: glass/polythene/iron/aluminium/PVC [3]

2 Any three of: destroys hedgerows/noise pollution/destruction of habitats/eyesore [3]

3 Iron ore/haematite [1]; limestone/calcium carbonate [1]; coke [1]; hot air [1]

4 Red-brown [1]; pungent [1]; gas [1] evolved

5 2Cl− → Cl2 + 2e−

6 Decomposition [1]; using a direct current of electricity [1]

7 Graphite/carbon [1]

8 a) Positive electrode [1]; b) Negative electrode [1]

9 Liquid/solution [1]; that conducts electricity [1]; and is decomposed by it [1]

10 Unreactive [1]; good conductor of electricity [1]

11 Bauxite [1]; cryolite [1]

12 Fe2O3 + 3CO → 2Fe + 3CO2 [3]

13 Carbon reacts with oxygen [1]; forming carbon dioxide gas [1]; or C + O2 → CO2 [2]

14 Al3+ + 3e− → Al [3]

15 Any three of: saves resources/less mining/less use of energy/less destruction of habitats/fewer eyesores created [3]


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Answers to Revision Questions - hodderplus.com to Revision Questions 1 Elements, Mixtures and Compounds 1 a) A substance that consists of only one type of atom [1] ... Al 2 (SO 4)