44
M1. (a) causes dust pollution 1 increases traffic 1 (b) (i) decomposition 1 (ii) 44(g) 1 (c) (calcium) hydroxide 1 (calcium) carbonate 1 substances must be in the order shown [6] M2. (a) calcium oxide 1 calcium hydroxide 1 calcium carbonate 1 substances must be in the order shown

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Page 1: Web view• hard. do . not . accept flexible ... mark unless they say add water to the calcium oxide. 1 (ii) magnesium hydroxide +hydrochloric acid. 1

M1.         (a)     causes dust pollution1

increases traffic1

(b)     (i)      decomposition1

(ii)                44(g)1

(c)     (calcium) hydroxide1

(calcium) carbonate1

substances must be in the order shown[6]

 

 

M2.          (a)     calcium oxide1

calcium hydroxide1

calcium carbonate1

substances must be in the order shown

(b)     (i)      strength of mortar decreases (as volume of sand increases)1

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(ii)     400 (cm3)1

because the height_ the metal ball dropped from shouldbe 42 cm and not 37 cm

accept because the other results show that the height_ the metal ball dropped from should have an interval of 6cm

1

(c)     contains aggregateallow bonding is stronger

1[7]

 

 

M3.          (a)     (i)      copper1

(ii)                50p1

(iii)               25 (%)1

(b)     any two from:

•        high value of copperallow copper is expensive or contains other metals (that may have higher value now)

•        less copper available or copper ores exhausted /only low-grade ores available

allow copper is non-renewable

•        high demand for copper

•        inflation of prices2

[5]

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M4.          (a)     (i)      because large amounts of energy would be needed toextract the copper

accept because it is labour-intensive to extract copper from this landaccept because copper would have to be extracted from a large area of land (owtte)

1

(ii)     any one from:

•        produces large amounts of solid waste

•        atmospheric pollution from carbon dioxide / sulfur dioxide

•        more lorries / traffic1

(b)     (i)      iron is cheapaccept iron is much more abundant than copper

1

(ii)     iron displaces copper from solutions of its saltsaccept iron is more reactive than copper

1

(c)     (i)      any two from:

•        less expensive / energy to extract the small amountsof copper

•        plants will remove carbon dioxide from the atmosphereas they grow

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•        can release energy when plants are burned2

(ii)     not continuous as it takes a long time for plants to growaccept supply not continuous as plants only harvested once / twice a year

1[7]

 

 

M5.          (a)     any two points one mark eachaccept comparison between aluminium and iron

aluminium has:

•        a low densityaccept lighter or fewer pylons

•        a good conductor of electricity

•        does not corrode or rustdo not accept does not react with airdo not accept last longer

2

OR

•        iron has:

•        high density

•        is a less good conductor (of electricity)

•        rusts or reacts with air

(b)     any 5 from:

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•        employment of people or cost of employment

•        depletion or use of resourcesdo not accept depletion here

•        cost of energy resources

•        cost of machines or buildings

•        pollution by noise from traffic or quarrying

•        air pollution by dust or traffic fumes

•        danger of traffic on roads

•        damage to landscape (eyesore)

•        damage to habitats of wildlife

•        lowers the value of houses nearby

•        subsidence or vibration can affect roads or houses

•        providing raw materialsdo not accept danger or falling in

5[7]

 

M6.          (a)     calcium carbonatenot formula

1

(b)     calcium carbonate → calcium oxidenot common namesallow correct formulae

1

+ carbon dioxide1

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(c)     calcium hydroxidenot formula

1

(d)     CaO + H2O → Ca(OH)2

allow if doubled

all formulae correct, no extra ones1

balanced1

(e)     filtrationallow centrifugation

not decantingnot evaporation, crystallisation

1

(f)      electrolysis stated or implied

          molten MgO / magnesium oxide is ionic / Mg2+ goes to cathodenot just heated

1

or add sodium / K / Ca / Li / a more reactive metal1

displaces Mg / reduces Mggive no marks if reference made to reduction by C or H

1[9]

 

M7.         (i)      a reaction in which the products canbe changed back to reactants

accept a reaction that can go forwards or backwards

1

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under certain conditions1

(ii)      Mr CaCO3  =  1001

Mr CaO  =  561

mass of CaO  =  140 (tonnes)1

mark consequentially[5]

 

 

M8.          (a)     limestoneclay

both for 1 mark1

(b)     watersandcrushed rock

for 1 mark each1

[4]

 

M9.          (a)     (i)      clayfor one mark

(ii)     calcium oxide / quicklime / CaOfor one mark

(iii)     sensible answers such as cost of fuel etc. / accept a wide range

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of appropriate answersfor one mark

3

(b)     sandgravel (owtte) e.g. crushed rockwater

any two for 1 mark each2

[5]

 

M10.          (a)     unreactive / near bottom of reactivity series1

(b)     carbon more reactive / higher up reactivity series1

(c)     very reactive / near top of reactivity series1

          cannot use displacement methods / can only be extracted by electrolysis / hadto wait discovery of electricity

1[4]

 

M11.          (i)      zincaccept Zn

1

          iron onlyaccept Fe

1

          copperaccept Cudo not credit iron

1

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(ii)      iron1

(iii)     copper or iron or manganeseaccept Cu or Fe or Mn

1[5]

 

M12.          (a)     This part was not marked1

(b)     electrolysis1

          because calcium is more reactive (than aluminium or carbon)accept it is more reactiveor very reactive

1

OR

in a blast furnace1

          because calcium is less reactive (than carbon or lower)1

(c)     any equation from1 mark for correct formulae1 mark for balancing

2ZnO  +  C  →  2Zn  +  CO2

ZnO  +  CO  →  Zn  +  CO2

ZnO  +  C  →  Zn  +  CO1

[5]

 

##

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          from limestone/marble;from calcium carbonate;action of heat/thermal decomposition;(other product is) carbon dioxide

any three for 1 mark each[3]

 

-

M14.          (a)     (i)      limestone / chalk / marble1

(ii)     breakdown / splits up1

with heat1

(iii)     to burn / react with air / oxygen1

         release energy / heat / exothermic / keeps temperature high1

(iv)    calcium carbonate → calcium oxide + carbon dioxide

calcium oxide1

correct equation1

(b)     (i)      exothermic / slaking / hydration not hydrolysis

1

(ii)     calcium hydroxide / slaked line1

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         mortar / neutralise acidity in soil / neutralise acid lake water / softenhard water / to make cement

not in agriculturenot to make lime water

1[10]

 

M15.          (a)     calciumcarbonoxygen

2 correct for 1 mark3 correct for 2 marks

2

(b)     cementglass

each for 1 mark2

(c)     (i)      allows coal to bum / flushes out CO2

for 1 mark1

(ii)     produced by burning coalproduced by decomposition of limestone

each for 1 mark2

(d)     (i)      calcium oxide + water → calcium hydroxideor quicklime + water → slaked lime

for 1 mark(allow composite equation from these two)

1

(ii)     to neutralise it / because it is alkaline or basicfor 1 mark

1[9]

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M16.          (i)      (hot air) gives faster reaction makes coal burn faster(provides air / oxygen to help to) allow the coal to burn / helps combustionflushes out the waste / gases / carbon dioxide

any one for 1 mark1

(ii)      decomposition of limestone yields carbon dioxide (owtte)the combustion / burning of coal produces carbon dioxide (owtte)

each for 1 mark2

[3]

 

M17.          (a)     good (electrical) conductorallow low reactivity / resistance to corrosiondo not accept heat conductor

1

(b)     a mixture of metalsaccept contains more than one type of metal

1

(c)     (i)      any one from:

•        eyesore

•        destruction of habitats

•        pollution of water

•        dust pollution

•        noise

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•        traffic pollution1

(ii)     acid rainallow sulfur dioxide is a pollutant

1

(d)     (i)      running out of copper (ores)1

(ii)     any two from:

•        any specific example of using less copper

•        reuse / recycleallow do not throw copper / brass away

•        use low-grade copper ores

•        use other metals / materials in place of copper2

[7]

 

M18.          (a)     any three from:

•        resources / aluminium / ores are conservedaccept converse argument

•        less / no mining or less associated environmental problemseg quarrying / eyesore / dust / traffic / noise / loss of land / habitat

ignore just pollution

•        less / no waste (rock) / landfilldo not accept ‘wastes 50% of the ore’

•        no purification / separation (of aluminium oxide)

•        (aluminium extraction / production) has high energy / electricity / heat / temperature requirements

•        less carbon dioxide produced

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accept no carbon dioxide producedignore references to cost

3

(b)     statementignore density

1

          linked reasoneg(pure) Al / it is weak / soft (1)as layers / rows can slide (over each other) (1)oralloy / other metals / they make it stronger / harder (1)stops layers / rows sliding over each other (1)accept disrupts the structure owtte if no other mark awardedaccept to form an alloy or to change properties for 1 mark

1[5]

 

M19.          (a)     (an alloy) that can return to its original shape (after being deformed / bent / twisted)

accept (on heating / cooling) it returns to its shape

1

(b)     any two from:

•        brass / it is a mixtureaccept brass / it is not pure

•        zinc changes structure / disrupts patterns or layers

•        copper metal atoms / layers able to slide over each otheraccept zinc prevents atoms / layers sliding over each other

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2

(c)     (i)      oxygen / O2 / O1

(ii)     lead remains (in furnace) because of its high boiling point1

         zinc boils / evaporates (out of furnace) because of its low boiling point 1 if neither mark awarded then allow 1 mark for different boiling points

ignore references to melting points1

[6]

 

M20.          (a)     (i)      calcium oxide / CaO1

         carbon dioxide / CO2

products can be in either orderignore chemical names other than calcium oxide or carbon dioxide

1

(ii)     (thermal) decompositionaccept endothermic

1

(b)     (i)      (chemical) reaction / reactaccept calcium hydroxide / slaked lime producedignore incorrect products

1

         energy / heat released / exothermicignore gets hot / heats upif neither mark awarded then allow ‘mixing the chemicals heats up the coffee’ for 1 mark

1

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(ii)     any two from:

•        foil has been broken(*)

•        ring pull used(*)(*)if neither mark awarded accept ‘cannot / difficult to repair’ for 1 markignore button pushed

•        quicklime and / or water mixed / reactedaccept reaction not reversibleaccept cannot / difficult to replace quicklime / water / chemicals

2[7]

 

M21.          (a)     tungsten1

          has the high(est) melting pointaccept that metals other than tungstenare likely to melt

1

(b)     argon1

          is an unreactive gasaccept that gases other than argon are reactiveaccept that argon is a noble gas or in Group 0

1[4]

 

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M22.          (a)     1 / one1

          3 / three1

(b)     (i)      (wear safety) glasses / masks / glovesaccept do not handle hot objects / usetongs or accept other safety pointssuch as, ‘tie hair back’

1

(ii)     calcium oxideaccept quicklime

1

(iii)     carbon dioxide / CO2 is given offaccept a gas is given off

1

(d)     (i)      any two from:

•        dust / atmospheric pollution

•        noise

•        eyesore

•        destroys habitats

•        (extra) traffic

•        any other named pollution or description of pollution2

(ii)     any one from:

•        employment

•        increases local trade / makes money

•        future development of quarry recreation / park / lake / reservoir       do not accept cheaper houses / land /       new roads

1[8]

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M23.          (a)     (i)      contain enough metal to make it economical / worth while to extract

1

(ii)     reductionaccept displacementaccept redox

1

(iii)     Fe + CO2

do not accept Fe2 / Fe4

1

correct balancingaccept multiples and halves

2Fe2O3 + 3C → 4Fe + 3CO2

allow Fe2 / Fe4 as ecf1

(b)     Pure Iron

          (in pure metal all the atoms are the same size and) able to slip / slide over eachother – (property soft)

OWTTEignore references to molecules / particlesif they say ‘move’ both times, allow one mark but ‘crack’ or ‘split’ is wrong..

1

Cast iron

          (in cast iron) different sized atoms / larger atoms or structure is distorted / disrupted

OWTTE1

          so it is difficult for layers of atoms to slip / slide over each otherOWTTE

1

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(c)     any three from:

•        conserves / saves resources / metal ores

•        saves energy resources (used for extraction / processing)accept cheaper / saves money

•        decreases waste materials

•        decreases a named pollutiondo not accept acid rain

3[10]

 

M24.          (a)     (i)      any one from:

•        iron ore is a limited resource / non-renewable

•        iron is in high demand

•        provide jobs

•        economic advantage1

(ii)     any two from:

•        would damage (wildlife) habitats / countryside / greenfield sites

•        extra traffic

•        visual (pollution) / eyesore

•        noise (pollution) / sound (pollution)

•        dust (pollution)

•        river (pollution)

•        carbon dioxide (from traffic) / adds to greenhouse effect / globalwarming

•        damage roads / buildings by vibrations / shockwaves2

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(b)     (i)      carbon monoxide / carbonaccept formulae CO / C

1

(ii)     atomsaccept (particles) are all the same (size) / type for one mark

1

are all the same (size) / type1

(iii)     any two from:

•        impurities / carbon / different (sized) atoms or elements or metals

•        changes the structure / disrupts the pattern or layers

•        prevents layers sliding over each other

•        it is an alloy2

[8]

 

M25.          (a)     any two from:

•        nitrogenaccept formulae N / N2

•        carbon dioxideaccept formula CO2

ignore CO

•        water (vapour) / steamaccept formula H2O

2

(b)     any three from:no mark for ‘limestone’ or ‘concrete’ on first line – mark advantages only

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limestone

•        abundant / localignore ideas of speed of production or easier to use

•        natural material or no ‘processing’ needed

•        relatively easy to cut

•        appearance better

concrete

•        raw materials are abundant

•        can be reinforced (by steel rods) / strong(er) / supported (by steel rods)

accept ‘can build higher’

•        concrete mixture can be poured / moulded / constructed on site

•        less reactive with acid rain / weathering / erosionignore density / extraction / quarrying / pollution / cost

3[5]

 

M26.          (a)     (i)      Cu2S + 2O2 2CuO + SO2

accept fractions and multiple1

(ii)     any two from:

•        sulfur dioxide       accept sulphur dioxide / sulphur oxide / SO2

•        causes acid rain       ignore other comments eg global warming / ozone / global dimming / greenhouse effect

•        consequence of acid rain eg kills fish / plants2

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(b)     any two from:

•        heat (copper oxide with carbon)

•        oxygen is removed by carbonaccept copper (oxide) loses oxygen

orcarbon gains oxygenaccept carbon oxide

or

carbon monoxide / carbon dioxide is produced

or

carbon displaces copperaccept a correct word or balancedsymbol equation

•        because carbon is more reactive than copperallow a correct comparison of reactivity

2

(c)     (i)      electrolysisaccept electroplating

1

(ii)     (electrical) wiring / appliances / coins / pipes / cladding forbuildings / jewellery / making alloys

1

or

named alloys

(d)     any three explanations from:

for recycling

•        less acid rain (pollution)

•        copper reserves last longer / conserved

or

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do not run out

•        energy for extraction (saved)

or

less energy required

•        less mining / quarrying

•        less waste (copper) / electrical appliances dumped

or

less landfill

         against recycling

•        collection problems

•        transport problems

•        difficult to separate copper from appliances

•        energy used to melt the collected copperignore electrolysis / pollutionignore ideas about less machinery / plantignore idea of cost

3[10]

 

M27.          clay1

limestone1

water1

 [3]

 

M28.          (a)     (i)      5(%)

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1

(ii)     0.35

 for 1 mark

2

(b)     (i)      reductionaccept (it’s) reduceddo not accept redox / deoxidation

1

(ii)     heat with / reduce / react with or (chemical) reaction1

         with a metal / element / substance higher in reactivityignore displaceaccept higher named elements or symbolaccept carbon monoxide / coal / cokecorrect word equation for 2 markscorrect formulas for 1 markcorrect balanced symbol equation for 2 marks

1

or

electrolysis:molten                                                                                        (1)electrolysis                                                                                 (1)

[6]

 

M29.          (a)     (very) small percentage / amount (in the Earth’s crust)

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any indication that there is a smallamount, eg not much (left)accept rare (elements) / rareraccept not commonly foundignore cannot find easilyignore hard to extract

1

(b)     (i)      oxygen / O  / O

do not accept O1

(ii)     any one from:

         •        potassium / K•        sodium / Na•        calcium / Ca•        magnesium / Mg

symbols must be correctwrite name and incorrect symbol, ignore symbol

1

(c)     (i)      heating (with) or hot air blown into furnaceaccept high temperatures or (very) hot

1

carbon / carbon monoxide / coke / coking coaldo not accept coal / charcoal accept balanced equation only

or:

         carbon reacts with O  or carbon / coke burning (1)accept balanced equation only CO / CO2

         CO reacts with the ore (1)for naming the reducing agent

1

(ii)     cost of melting ore / electricitymakes aluminium expensive (owtte)or (large amount of) electricity usedor because you have to use electrolysisor aluminium is higher in the reactivity series

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or aluminium is harder to reduceor unable to reduce with carbonor the cost of purifying the bauxite

do not accept harder to extract / producemore energy is not enough

1[6]

 

M30.          (a)     colour1

(b)     Fe2O3 or (Fe3+)2 (O2-)3

2 and 3 should be below halfway on Fe and O

1

(c)     (i)      4  4or correct multiples

1

(ii)     any two from:ignore references to malleable / ductile / conductivity / stiff / boiling point / density

•        high melting pointaccept can withstand high temperatures

•        strong / toughaccept not brittle

•        harddo not accept flexible

•        not (very) reactive2

[5]

 

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M31.          (a)     (i)      heat (the limestone)accept decompose limestoneaccept heat with coke

1

add water / slakedependent on 1st mark unless they say add water to the calcium oxide

1

(ii)     magnesium hydroxide +hydrochloric acid

1

         → magnesium chloride + water / H2O1 mark for each side of the equation(if a symbol equation is given then give 1 mark for correct formulae (all) and 1 mark for balancing)

1[4]

 

M32.          (a)     Marks awarded for this answer will be determined by the Qualityof Written Communication (QWC) as well as the standard of thescientific response.

No relevant content.0 marks

There is a brief description of the electrolysis of aluminium oxide.Level 1 (1–2 marks)

There is some description of the electrolysis of aluminium oxide.Level 2 (3–4 marks)

There is a clear, balanced and detailed description of theelectrolysis of aluminium oxide.

Level 3 (5–6 marks)

examples of the chemistry points made in the response

•        aluminium oxide is melted / made liquid

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•        aluminium ions are attracted to the negative electrode

•        at the negative electrode aluminium is formed oraluminium ions gain electrons

•        oxide ions are attracted to the positive electrode

•        oxygen is formed at the positive electrode or oxideions lose electrons

•        the oxygen reacts with carbon to make carbon dioxide orcarbon dioxide formed at positive electrode.

(b)     there are delocalised electrons / free electrons / electronswhich move within the aluminium / metallic structure

1

therefore these electrons are able to carry the current / charge1

if the candidates use the terms covalent / ionic / molecules / intermolecular incorrectly in the answer this will limit the mark to a maximum of 1.

[8]

 

 

M33.          (a)     atoms1

(b)     mixture1

          metal1

          structure1

          smart1

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(c)     (i)      any two from:

•        saves raw materials / iron ore

•        saves energy / fuelsaccept cheaper / saves money

•        make new / useful items

•        make money / it is economic

•        reduces pollutionallow less harmful for the environment

•        decreases cost of steel cans

•        reduces carbon dioxide emissions

•        decreases waste materials / use of landfill2

(ii)     any one from:

•        provide information / education of the need to recycle

•        legislate against / charge for waste

•        reward / pay people to recycleaccept fine people for not recycling

•        put labels on the cans

•        provide recycling bags / bins / areas1

[8]

 

M34.          (a)     (i)      11

         31

(ii)     nucleus1

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         electron1

(b)     (i)      methane / CH4

accept natural gasignore airdo not allow other gases

1

(ii)     carbon dioxide1

(c)     (i)      any two from:

•        medical risks

•        asthma

•        cancer

•        dirt

•        causes global warming / global dimming / greenhouse effect / acid rainignore deathaccept effect on healthaccept difficulty breathing/ lung diseaseallow smoke particlesallow harmful for the environment

2

(ii)     any two from:

•        have a test done / scientific evidence

•        independent (evidence)

•        comparison of smoke particles / when differentfuels used

•        medical evidence or more / less asthma attacks orcancer or dirt on cars

2[10]

 

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M35.          (a)     (Chromium =) 201

          in correct order

          (Nickel =) 8accept Chromium = 8 and Nickel = 20 for 1 mark

1

(b)     (i)      (because iron is made up of only) one type of atom1

(ii)     not strongignore soft / corrosive / flexibleaccept it rusts / corrodes or that it could wear awayaccept could change shape / bendaccept layers / atoms could slide (over each other)

1

(iii)     has different sized atoms / particlesorstructure is different/distorted / disrupted

accept not in layers or not regular1

         so it is difficult for layers / atoms / particles to slip / slide (over each other)

accept layers cannot slip / slide1

[6]

 

M36.          (a)     (i)      oxygen / air reacts with carbon / methane (to form carbon dioxide)

accept from the decomposition / reaction of

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calcium carbonateignore CO2 from the air

1

         nitrogen is (unreacted) from the air1

(ii)     CaO1

         CO2

any orderignore wordsany incorrect balancing max 1 mark

1

(b)     any one from:

•        more energy / efficientallow converse for present fuel

•        from a sustainable / renewable resource

•        produces less / no carbon dioxide / greenhouse gases / global warming

ignore no pollution / environmental damage

•        more profit or money for local economyaccept fuel is cheap(er)

•        more readily availableit = different fuel

1

(c)     (i)      any two from:

•        not near where people / residents liveaccept not between cement works and where people liveignore sensors are unsightly

•        not positioned where concentration of particles was likely to be highest

•        not positioned downwind2

Page 33: Web view• hard. do . not . accept flexible ... mark unless they say add water to the calcium oxide. 1 (ii) magnesium hydroxide +hydrochloric acid. 1

(ii)     the average / concentration was 1.8(ppm) or the average / concentrationwas below 2(ppm)

accept 1.8(ppm) is less than 2.0 (ppm)1

(iii)     any three from:

•        children / people suffering asthma attacks

•        result was an average

•        readings (at some (2/3) sensors) could have been higher than 2ppm

•        sensors did not detect particles below 0.5mm

•        small particles / particles below 0.5mm / 0.4mm / 0.3mm / 0.2mm could (still) cause cancer / asthmaignore global dimming or cars becoming dirty or position of sensors

3[11]

 

M37.          (a)     conducts (electricity) oraccept flexible

          allows electrons / current to flowignore conducts heat

1

(b)     electron1

(c)     (i)      lithium>copper>tungsten or

Page 34: Web view• hard. do . not . accept flexible ... mark unless they say add water to the calcium oxide. 1 (ii) magnesium hydroxide +hydrochloric acid. 1

         Li>Cu>Wall correctallow 1 mark for one metal in the correct position

2

(ii)     has high / highest melting pointaccept has high / highest boiling point

         or

         can withstand the highest temperature1

(d)     unreactive1

[6]

 

M38.          (a)     (i)      3 / three1

(ii)     5 / five1

(b)     any one from:

•        less / no transportaccept less / no distance

•        less / no (fossil) fuel usedignore references to carbon dioxide / carbon emissions

1

(c)     (i)      carbon dioxide / CO2

for a correct emission1

Page 35: Web view• hard. do . not . accept flexible ... mark unless they say add water to the calcium oxide. 1 (ii) magnesium hydroxide +hydrochloric acid. 1

         (causes) global warming / climate change / greenhouse gasexplanation must be correct for named emissionignore ozone layer

         or

         (cement) particles / smoke (1)

         (causes) asthma / dust / (global) dimming (1)accept breathing problems

         or

         sulfur dioxide / SO2 / nitrogen oxides / NOx (1)

         (causes) acid rain (1)do not accept nitrogen or water vapour for emissionsdo not accept no named emission

1

(ii)     absorb / trap / capture / filter / pass through water / scrub / electrostatic attraction

ignore condense / off setting / different fuel1

[6]

 

M39.          (a)     (i)      calcium oxide / quicklimeallow calcium monoxidedo not accept calcium dioxideignore chemical formulae

1

(ii)     any three from:

•        carbon dioxide / CO2

•        (carbon dioxide) reacts (with the calcium hydroxide / slakedlime / plaster)

Page 36: Web view• hard. do . not . accept flexible ... mark unless they say add water to the calcium oxide. 1 (ii) magnesium hydroxide +hydrochloric acid. 1

allow reaction 3 identifieddo not allow incorrect reactionignore mixes, unless they state the correct product

•        limestone / calcium carbonate / CaCO3 formsallow marble / chalk

•        water is lost / evaporatesit = plasterallow moistureignore dries

3

(b)     (i)      as the amount / volume of sand decreases the strength of themortar increases

accept as sand decreases the mortar is stronger / harder to crackallow as sand decreases the mortar increasesallow converseignore references to height_ of metal ball

1

(ii)     any two from:

•        400 / 5th result is anomalousaccept two results (36 and 37 / 400 and 500 / 4th and 5th) are almost the sameaccept result at 400 should be 42

•        the interval between the others is similar or the intervalis about 6/7allow the other results fit a pattern / are on a straight line

•        he has only one set of resultsallow he has only done it onceignore reliable

2[7]

 

Page 37: Web view• hard. do . not . accept flexible ... mark unless they say add water to the calcium oxide. 1 (ii) magnesium hydroxide +hydrochloric acid. 1

M40.          (a)     (i)      reacts with carbon / Caccept burns / oxidises carbon

1

         carbon dioxide / CO2 / gas is formed / given offaccept carbon monoxide / COaccept correctly balanced equation for 2 marksignore state symbols

1

(ii)     change / improve propertiesaccept any specific propertyaccept to make alloys / special steelsignore brittle

1

(b)     any two from:

•        to conserve ores / ironaccept ores / iron are non-renewable / non-sustainableallow less quarrying / mining

•        to prevent the use of landfillsallow reduce waste

•        to conserve energy / fuelaccept fossil fuels are non-renewable

•        to reduce carbon / carbon dioxide emissions

•        to meet EU / International targetsignore costs / demand

2[5]