1CCEA GCSE Science Double Award

Exam practice answers

Biology

Chapter 1 Cells1 (a)(i) A–chloroplasts;B–cellmembrane;

C–cellwall [3](ii) B;D;E [3]

(b)Nucleus;cytoplasm [2](c)Plasmids;non-cellulosecellwall [2]

2 (a)Addwater/iodine;addacoverslip;placetheslideonthemicroscopestageandfocusatlowpower [3]

(b)Thetissueistakenfrompartofanonionplantthatgrowsunderground [1]

Chapter 2 Photosynthesis and plants1 (a)carbondioxide+water> glucose+oxygen [2]

(b)(i) Chlorophyll [1](ii) Chloroplasts [1]

(c)Areactioninwhichenergyisabsorbed [1]2 (a)(i) Leaveinadarkplacefor48hours [1]

(ii)Toensurethatanystarchpresentisonlyproducedduringtheinvestigation(tomaketheinvestigationvalid) [1]

(b)Addtheveryhot/boilingwaterfromanelectricalkettleanddonotuseBunsenburnersasethanolisflammable [1]

(c)Toremovechlorophyll;tomakeanycolourchangewithiodineeasiertosee [2]

3 Anyfourfrom:• AtAphotosynthesisisoccurringmuchfaster

thanrespiration• Somorecarbondioxideabsorbedfrom

atmosphere• Asgetsclosertoendofday(B)lightlevels

reduce• Soless/nophotosynthesis• Morerespirationthanphotosynthesis

resultsincarbondioxidebeingaddedtotheatmosphere [4]

4 (a)(i) Palisademesophyll [1]

(ii)LayerXisclosertolight;hascellspackedmoretightlytogether;hasmorechloroplasts [3]

(b)(i) Guardcells [1](ii)Toopenandclosethestomatalpore [1]

Chapter 3 Food and energy1 (a)

ReagentInitialcolour

Endcolouriffoodpresent

Blue-black

Blue

Ethanol

[3]

(b)Benedict’s [1]2 (a)Aminoacids [1]

(b)Ineachproteintheaminoacidscanbebuiltupinadifferentsequence [1]

(c)(i) Antibody/enzyme/otherappropriateexample [1]

(ii)Muscle/otherappropriateexample [1]3 (a)temperaturerise=47

energy=25×47×4.2=4935 [2](b)Holdthefoodthesamedistanceawayfrom

theboilingtube [1](c)Heatenergylosttotheair/usedinheating

theglass/leftinburnedfoodremains [1]

Chapter 4 Enzymes and digestion1 (a)Enzymesarebiologicalcatalysts;thatspeed

uptheratesofreactions [2](b)

EnzymeFooddigested(substrate)

Productsofdigestion

Glucose

Protease

Fat

[3]

(c)Onlyonesubstrate;canfittheactivesiteofanenzyme [2]

2 (a)(i) 40°C [1](ii) Lowratesofcollisionbetweensubstrate

andenzyme;duetoreducedkineticenergyatlowtemperature [2]

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(iii) Reducedenzymeactivityashighertemperaturesdenaturetheenzyme;substrateisnolongerabletofittheactivesite [2]

(b)Inhibitorissamegeneralshapeassubstratemolecule;socanfitintotheactivesite,preventingthesubstratemoleculefitting;whichreducesenzymeactivity [3]

Chapter 5 The respiratory system and cell respiration1 (a)glucose+oxygen >carbondioxide+water+energy [2]

(b)Lacticacidisproducedinmuscleandalcoholinyeast;inyeastcarbondioxideisproducedbutnotinmuscle [2]

2 Exercisecausestherateofbreathingtoincrease;asthebody(muscle)cellsrequiremoreoxygen;fortheincreasedrespirationtakingplace [3]

3 (a)(i) Increasedareaacrosswhichgasescandiffuse [1]

(ii) Manyalveoli [1](iii) Onelayerofalveolarcells;onelayerof

cellsincapillaries [2](b)Thecellssurroundingtheairspacesuseup

oxygeninrespiration;creatingaconcentrationgradientofoxygen(lessoxygeninspacesthanatmosphere) [2]

Chapter 6 Coordination and control1 (a)(i) Associationneurone [1]

(ii) Synapse [1](iii)Spinalcord [1](iv) A [1](v)B [1]

(b)Shortestpossiblenervepathway;asbypassesthebrain [2]

2 (a)Messenger;blood [2](b)(i) Pancreas [1]

(ii) Amealrichincarbohydrate [1](iii) Glucoseconvertedtoglycogen;more

glucoseabsorbedfromblood(andrespired) [2]

3 (a)(i) (141–94)=47 (47/94)×100=50% [2](ii)Type1isalsoincreasingover

time/therearemorepatientswithtype2diabetesthantype1 [1]

(iii)Anytwofrom:• Toomuchsugarinthediet• Increaseinobesity• Lessexercisebeingtaken [2]

(b)Anytwofrom:• Eyedamage• Kidneydamage• Heartdisease• Strokes [2]

4 (a)Urea(b)(i) Controllingthewaterbalancein

thebody [1](ii) Thebodylosesalotofwaterinsweat;

somorewaterisreabsorbedinthekidneys [2]

(iii) ThemoreconcentratedthebloodthemoreADHreleased;somorewaterreabsorbedbythekidney [2]

5 (a)(i) Phototropism [1](ii) Anytwofrom:

• Morelight• Morephotosynthesis• Moregrowth [2]

(b)Auxinproducedinthetip;andpassesdowntheshadedsideofthestem;cellsonshadedsidegrowmore(becomelonger) [3]

Chapter 7 Ecological relationships and energy flow1 (a)Thenumberofindividualsofaparticular

speciesinanarea [1](b)Userandomnumberstopositionanumber

(e.g.20)ofquadrats;calculatetheaveragenumberofdaisiesinthequadrats;multiplytheaveragepersquaremetrebythenumberofsquaremetresintheplayingfield(orequivalentcalculation) [3]

2 (a)Flowofenergy/showingwhateatswhat [1] (b)Ananimalthatfeedsonproducers [1] (c)3 [1]3 (a)Photosynthesis [1]

(b)Fossilisation [1]

Chapter 8 Osmosis and plant transport1 PutsolutionAintoViskingtubingandtietheends

tightly;drythesurfaceoftheViskingtubingandweigh;placetheViskingtubingintoabeakercontainingsolutionB;afterafewhoursremovethe

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Viskingtubingfromthebeaker,dryandre-weigh;iftheViskingtubinggainedinmassthenitcontained10%sucrose(aswaterhadmovedbyosmosisfromthe5%sucrosetothe10%sucrose)/ifitlostmassthenitcontainedthe5%sucrose(aswaterhadmovedbyosmosisoutoftheViskingtubing) [5]

2 (a)(i) 20%;decrease [2](ii) Theinitialmassesaredifferent [1](iii) Anytwofrom:

• Sametypeandsizeofplant• Plantsgivensameamountofwater

(beforetheinvestigation)• Sametemperature• Samehumidity• Samelightintensity. [2]

(iv) Theplantinwindyconditionslostmoremass;morewaterlostintranspiration;windyconditionsincreasetherateofevaporation [3]

(b)Plantcellsaremoreconcentratedthantheirsurroundings;waterentersthecellsbyosmosis;pushingthecellmembraneagainstthecellwall,makingthecellfirm [3]

3 (a)(i) A–Thecarrotcylinderlostwaterbyosmosis;aswatermoveddowntheconcentrationgradient(fromcarrottothesolution)

B–Therewasnochangeinmassastherewasnooverallmovementofwaterinoroutofthecarrotcylinders;asthecarrotcylindersandthesolutionwereatthesameconcentration [4]

(ii) Changeinlengthonlymeasureschangeinoneplane(massmeasurestheentirechange);balancesaremoreaccuratethanusingarulertomeasurelength(particularlyiftheedgesarenotstraight) [2]

(iii) Sametype/ageofcarrots/carrotscutinsameplane/carrotcylindersthesamethickness [1]

(b)Anytwofrom:• Support• Transport• Transpiration• Photosynthesis [2]

Chapter 9 The circulatory system1 (a)(i) Tocarryoxygen [1]

(ii)Biconcaveshape;givesalargersurfaceareaforabsorbingoxygen

and/or

Nonucleus;morespaceforcarryinghaemoglobin

and/orcontainiron;tohelpcarrytheoxygen [4]

(b)Theyconvertfibrinogentofibrin;causingbloodclottingandscabformation [2]

2 (a)(i) Providesstrength [1](ii) Allowsthearterytoexpandandrecoil;as

bloodpulsesthrough [2](b)Thebloodisunderlesspressureintherenal

arterysotherenalarterywillexpand(andrecoil)less [1]

(c)Pulmonaryartery [1]3 (a)(Rightatrium)–rightventricle–pulmonary

artery;lungs;pulmonaryvein–leftatrium–(leftventricle) [3]

(b)Coronaryarteries [1]4 (a)(i) 108–68

=40 [2](ii) 5minutes [1](iii)Anytwofrom:

• Lowerrestingheartrate• Doesn’triseashigh• Shorterrecoverytime(returnstonormal

faster) [2](b)Strengthenstheheartmuscle;increased

cardiacoutputwhenatrest [2]

Chapter 10 DNA, cell division and genetics1 (a)AlltheDNAinanindividual [1]

(b)(i) Onlyadeninewillpairwiththymine;onlycytosinewillpairwithguanine [2]

(ii) ThesequenceofDNA;alongthecodingstrandisdifferentineveryone [2]

(c)Eachsequenceofthreebases;codesforaparticularaminoacid; [2]

2 (a)Mitosisproducescellswithchromosomesthataregeneticallyidenticaltoeachother;andtotheparentcells;meiosisproducescellswithhalfthenumberofchromosomesoftheparentcell;andthesecellsaregeneticallydifferentfromeachother [4]

(b)Eitherchromosomeinapairofchromosomescancombinewitheitherofthechromosomesinanotherpairingameteformation(andsoonforall23pairsinhumans);thisisindependentassortment [2]

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3 (a)(i) 3:1 [1](ii) Randomwhichgametesfromthemale

combineswitheachfemalegamete [1](b)

R r

R RR Rr

Rrr rr

Let R = red flowers; r = white flowers

Gametes[2];offspring[1] [3]4 (a)3 [1]

(b)Everygenerationisaffected/noexamplesofanindividualhavingHuntington’sdiseasewithoutaparenthavingthecondition [1]

(c)1in2chanceofnextchildhavingHuntington’sdisease;1in2chanceofbeingaboy;sooverallchance=1in4 [3]

5 (a)plasmid–humangene–bacterium [1](b)Theplasmidiscut;usingrestrictionenzymes;

sameenzymesforbothhumanDNAandplasmid;toallowcomplementarystickyendstoform [4]

(c)Anytwofrom:• Canproducethelargeamountsrequired• Humaninsulinisslightlydifferentin

structurefromtheinsulinofotheranimals• Theriskofspreadingviruseswhenusing

animalinsulin• Manypeoplewithdiabetesareethically

opposedtousinganimalinsulin [2]

Chapter 11 Reproduction, fertility and contraception1 (a)Toproducesperm [1]

(b)(Testes)–spermtubes;prostate;urethrainpenis [3]

(c)Anytwofrom:• Arehaploid• Tail/flagellumforswimming(tothefemale

gamete)• Mitochondriaforenergyproduction [2]

2 Anythreefrom:• Fertilisedegg(zygote)passesfromtheoviduct

intotheuterus• Zygotedividesbymitosis• Toformaballofcells/embryo• Implantsintotheuterinelining/liningof

uteruswall [3]

3 (a)Thereleaseofanegg/ovum;byanovary [2](b)Oestrogenstimulatesovulation;promotes

repairoftheuterinewall;progesteronecontinuesthebuild-upoftheuterineliningafterovulation(inpreparationforpregnancy) [3]

4 (a)Topromotethereleaseofeggs/ovabytheovaries;toensuretheuterineliningisbuiltup [2]

(b)Anytwofrom:• Costofhormonetreatment• Extractionofeggs/ovaisaveryspecialised

role(specialiststaffandequipment)• Placingembryosinuterusisaveryspecialist

role(specialiststaffandequipment)• Anyotherappropriateanswer [2]

(c)Fertilisationinthelaboratory/outsidethebody [1]

5 (a)Thenumberofvasectomiesincreaseswithageuntilages40–49;thenfallswithage [2]

(b)Menaged20–24maynotbesurethattheydonotwantchildrenlater/menaged40–49mayalreadyhaveafamily/areclearerabouttheirlifepath/otherappropriateanswer [1]

(c)Spermtubesarecut;spermcannottraveltothepenis/leavethemalebody [2]

Chapter 12 Variation and selection1 (a)Individualscanbeplacedintodistinctgroups

easilywithnooverlap [1](b)Tonguerolling/handdominance/other

appropriateanswer [1]2 Onlythefastestpredatorscaughtprey;asprey

becomingfastersohardertocatch;soonlythosepredatorsbestadapted(i.e.fastest)survivedandreproduced(passingtheirgeneson) [3]

3 Inindustrialareastheblackmothsarebettercamouflaged/lighterformslesswellcamouflaged;thelightermothsaremorelikelytobepredated/blackformslesslikelytobepredated;numberofblackmothsincreasesovertime/numberoflightmothsdecreasesovertime [3]

4 Similar–thebestmalesandbestfemalesareusedinthebreedingprocess/itishumans,ratherthannature,doingtheselection

Difference–theprocessismuchfaster(severalgenerationsarenotrequiredtoproducehigh–qualityoffspring [2]

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Chapter 13 Health, disease, defence mechanisms and treatments1 (a)Tuberculosis;itisabacterialdiseaseandthe

otherdiseasesareviral [2](b)Thedoctorwasnotclearastoexactly

whichtypeofbacteriacausedtheinfection;anantibioticwouldworkquickerthanavaccination [2]

2 (a)Antibodiesareacomplementaryshapetotheantigensonamicroorganism;theylatchonthemicroorganisms;immobilisingthem/preventingthemfromspreadingaroundthebody [3]

(b)Active [1](c)Phagocytesengulfharmfulmicroorganisms;

anddigestthem [2]3 (a)Anytwofrom:

• Excessdietaryfats• Smoking• Lackofexercise• Stress [2]

(b)Thestentispushedtothesiteofablockageinabloodvessel;andthenexpandedtoholdthevesselopen [2]

4 (a)Nicotine [1](b)Carbonmonoxidecombineswiththeredblood

cells;preventingoxygenfromcombining;thereforelessoxygeniscarriedtothebodycellsforrespiration [3]

5 (a)Benignandmalignant [1] (b)Benignisencapsulated/doesn’tspreadaround

thebody(orconverse) [1]

Chemistry

Chapter 14 Atomic structure 1 numberofprotonsin(thenucleusof)anatom [1] 2 (a) proton:relativemass=1andrelativecharge=

+1 [1] (b) electron:relativemass=

11840and

relativecharge=−1 [1] (c) neutron:relativemass=1andrelativecharge=0

[1] 3 Atomsofthesameelement/withthesamenumber

ofprotons[1]butwithadifferentmassnumber/differentnumberofneutrons[1].

4 Atomscontainthesamenumberofprotonsandelectrons [1]

5 (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]

6 (a) 2,8 [1](b) 2,8 [1](c) 2,8 [1](d) 2,8 [1](e) 2,8,8 [1]

7 (a) Al3+ O2− F− [1](b) Al3+ [1](c) Cl− [1](d) hydrideion [1]

8 (a) 3− [1](b) phosphorus [1](c) phosphide [1]

9 20protonsand20neutrons[1]inthenucleus[1]

20electrons[1]arranged2,8,8,2[1]

10 relativeatomicmass=

× × × × (5.8 54)+ (91.8 56)+ (2.2 57)+ (0.2 58)100 [1]

= 5591100

=55.91[1]=55.9[1] to1decimalplace

Chapter 15 Bonding, structures and nanoparticles 1 Amixtureoftwoormoreelements,atleastone

ofwhichisametal[1]andtheresultingmixturehasmetallicproperties[1].

2 anytwofrom:conductselectricity/light/fasterrecharge/lessrequired [2]

3 attraction[1]betweenoppositelychargedions[1] 4 (a) ionic [1]

(b) covalent [1](c) metallic [1]

5 (a) topunbondedpairofelectronslabelled [1](b) covalent [1](c) vanderWaals’forcesofattraction [1](d) NH3 [1]

6 pairofelectrons[1]sharedbetweentwoatoms [1]

7 (a)

××

××

××

×Cl Cl

chlorine, Cl2

[1]

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(b) [1]

O

H×

×H

water, H2O

××

× ×

(c)

carbon dioxide, CO2O=C=O

×

×O C

×

×O

[1]

8 ThevanderWaals’[1]forcesofattractionbetweenthemoleculesareweak[1]andrequirelittleenergytobreak[1].

9 Eachcarbonatom[1]covalently[1]bondedtofour[1]othercarbonatomsinatetrahedral[1]arrangement,andthestructureisgiant[1].[max.3]

10 Delocalisedelectrons[1]canmoveandcarrycharge[1].

11 Aregulararrangement/lattice[1]consistingoflayers[1]ofpositiveions/cations[1]heldtogetherbymetallicbonding,whichistheattractionbetweenthepositiveionsandthedelocalisedelectrons[1]. [max.4]

12 (a) sodiumandiron [1](b) sodium,grapheneandiron [1](c) ammonia,hydrogenandcarbondioxide [1]

13 (a) Insodiumchloridesolutiontheions[1]arefreetomoveandcarrychargebutinsolidsodiumchloridetheionscannotmove[1].

(b) ioniclattice [1](c) Strongionicbonds[1]requiresubstantial

energytobreak[1].

Chapter 16 Symbols, formulae and equations 1 (a) NaF [1]

(b) MgO [1](c) K2O [1](d) BaCl2 [1]

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

3 sodiumcarbonate=Na2CO3[1];sodiumhydrogencarbonate=NaHCO3[1]

4 (a) carbondioxide [1](b) potassiumnitrate [1](c) copper(ii)carbonate [1](d) hydrogenfluoride [1](e) magnesiumsulfate [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+3½O2→2CO2+3H2O)11 (a) BaCl2(aq)+K2SO4(aq)→BaSO4(s)+

2KCl(aq) [4](b) Ba2++SO4

2−→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) (i) Mg+Cu2+→Mg2++Cu [2]

(ii) Zn+2H+→Zn2++H2 [3](iii)CO3

2−+2H+→CO2+H2O [3](b) (i) Mg→Mg2++2e−andCu2++2e−→Cu [6]

(ii) Zn→Zn2++2e−and2H++2e−→H2 [6]

Chapter 17 The periodic table 1 (a) alkalimetals [1]

(b) alkalineearthmetals [1](c) halogens [1](d) noblegases [1]

2 K→K++e− [2] 3 phosphorus,P [1] 4Anyfourfrom:floats/fizzes/movesaboutthe

surface/heatreleased/colourlesssolutionformed/disappears/lilacflame/crackleorexplosion [4]

5 (a) yellowgas [1](b) yellow-greengas [1](c) red-brownliquid [1](d) grey-blacksolid [1](e) colourlessgas [1]

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

7 group6 [1] 8 (a) nitrogen[1];oxygen[1];fluorine[1];

bromine[1](b) carbon/sulfur [1](c) sodium [1]

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(d) iron [1](e) oxygen[1];nitrogen[1];fluorine[1]

9 shiny surface goesdull [1]10 fluorine [1]11(a)white[1];(b)grey-black[1];(c)black[1];

(d)blue[1];(e)green[1]12 Cl2+2e−→2Cl− [3]13 anythreefrom:largetroughofwater/small

pieceofsodium/safetyscreen/gloves/glasses/tongstohandlesodium/removeoilfromsurfaceofsodium [3]

14 (a) 2Na+2H2O→2NaOH+H2 [3](b) Sodium is less dense than water. [1]

15 anytwofrom:inorderofatomicmass(weight)/nonoblegases/noblockoftransitionmetals/noatomicnumber/fewerelementsorgaps/noactinidesorlanthanides [2]

Chapter 18 Quantitative chemistry I 1 carbon-12 [1] 2 (a) 98 [1]

(b) 74 [1](c) 342 [1](d) 138 [1](e) 162.5 [1]

3 molesCaCO3=5/100=0.05 [1] molesCaO=0.05 [1] massCaO=0.05×56=2.8g [1] 4 molesMg=1.2/24=0.05 [1] molesMgO=0.05 [1] massMgO=0.05×40=2g [1] 5 (a) molesofFe2O3=40/160=0.25 [1]

(b) molesofNa=46/23=2 [1](c) limitingreactant=Fe2O3 [1](d) molesofiron=0.25×2=0.5 [1](e) massofiron=0.5×56=28g [1]

6 (a) (36/171)×100[1]=21.1%[1](b) (180/286)×100[1]=62.9%[1]

7 H2O2 [1] 8 (a) molesP=1.55/31=0.05 [1] molesofPCl5formed=0.05 [1] massPCl5(theoreticalyield)=0.05×208.5

=10.425g [1](b) (8.34/10.425)×100[1]=80%[1](c) sidereactions/notallphosphorusreacts [1]

Chapter 19 Acids, bases and salts 1 asolublebase [1] 2 anytwofrom:copper(ii)oxide/copper(ii)

carbonate/copper(ii)hydroxide [2] 3 (a) purple/darkblue[1];12–14[1]

(b) red[1];0–2[1](c) blue[1];9–11[1]

(d) yellowororange[1];3–6[1](e) green[1];7[1]

4 H+ [1] 5 Anymetaloxideor metal hydroxide,suchas

magnesiumoxide,copper(ii)oxide,sodiumhydroxideetc. [max.2]

6 0.5mol/dm3 [1] 7 H+(aq)+OH−(aq)→H2O(l) [3] 8 (a) Mg+2HCl→MgCl2+H2 [3]

(b) Mg(OH)2+2HCl→MgCl2+2H2O [3](c) CaCO3+2HCl→CaCl2+CO2+H2O [3]

9 (a) heatreleased[1];bubblesofgas[1];soliddisappears[1];colourlesssolution[1][max.3]

(b) bubblesofgas[1];greensoliddisappears[1];solutionchangesfromcolourlesstoblue[1];heatreleased[1] [max.3]

10 sodiumchloride [1]11 (a) red [1]

(b) red [1](c) orange [1]

12 hydrogen[1];holdalitsplintatthemouthofatubeofit[1];listenforpop[1]

Chapter 20 Chemical analysis 1 (a) solidthatdissolvesinasolvent [1]

(b) liquidinwhichthesolutedissolves [1](c) mixtureofthesolutedissolvedinthesolvent [1]

2 Addwater[1]thenfilterthroughfilterpaper[1].Sandistheresidue[1];wateristhefiltrate[1].

3 fractionaldistillation [1] 4 (a) 3 [1]

(b) wateror other suitable solvent [1](c) 2 [1](d) 1and4 [1](e) 1 [1](f) notsoluble [1](g) solventfront [1]

5 (a) B=filterpaper[1];C=filterfunnel[1];D=conicalflask[1]

(b) residue [1](c) filtrate [1](d) sandmixedwithwater [1]

6 whitetoblue [1] 7 Nichromewire[1],dippedinconcentrated

hydrochloricacid[1].PlaceinsampleandheatsampleinblueBunsenburnerflame[1].Observeyellow/orangeflamecolour[1]forsodiumions.

Chapter 21 Reactivity series of metals 1 hydrogen [1] 2 anyfourof:floats/movesaboutthesurface/fizzes/

lilacflame/eventuallydisappears/explodesorcrackles/heatreleased/colourlesssolutionformed [4]

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3 2K+2H2O→2KOH+H2 [3] 4 anythreefrom:red-brownsolidappears/blue

solution/fadestocolourless/heatreleased [3] 5 Byheating[1]dampmineralwool[1]. 6 (a) Cu+2AgNO3→Cu(NO3)2+2Ag [3]

(b) nitrateion/ −NO3 [1](c) Cu+2Ag+→Cu2++2Ag [3]

7 Aluminiumhasaprotectiveoxidelayer. [1] 8 Greysolid[1]burnswithabrightwhitelight

[1],formingawhitesolid[1]. 9 (a) calcium [1]

(b) calcium [1](c) calcium,aluminium,zinc,copper [1]

10 2Ca+O2→2CaO [3]11 magnesium,manganese,chromium,nickel [1]12 2Cr+3Ni(NO3)2→2Cr(NO3)3+3Ni [3]13 Mg+Mn2+→Mg2++Mn [2]14 Allnitratesaresolubleinwater. [1]

Chapter 22 Redox, rusting and iron 1 Nitrogengainshydrogen[1]andgainofhydrogen

isreduction[1]. 2 (a) hydrogen [1]

(b) oxygen [1] 3 haematite/ironore[1];coke/carbon[1];

limestone/calciumcarbonate[1];hotair[1] 4 magnesium/zinc [1] 5 (a) hydratediron(iii)oxide [1]

(b) Redoxisoxidationandreductionoccurringsimultaneouslyinthesamereaction. [1]

6 oxygen[1];loss[1];oxygen[1];gain[1] 7 (a) Zn→Zn2++2e− [3]

(b) Cu2++2e−→Cu [3](c) Znequation [1]

8 Mg→Mg2++2e−[3];oxidation[1] 2H++2e−→H2[3];reduction[1] 9 Magnesiumisoxidised[1];zincionsare

reduced[1].10 water/moisture[1];air/oxygen[1]11 anytwoof:painting/oiling/greasing/plastic

coating/suitablemetalplatingorgalvanising [2]12 Fe2O3+3CO→2Fe+3CO2 [3]13Calciumcarbonateundergoesthermal

decomposition. [1] CaCO3→CaO+CO2 [2] Calciumoxidereactswithsilicondioxidetoformcalciumsilicate/slag. [1]

CaO+SiO2→CaSiO3 [2]14 (a) Carbongainsoxygen[1]andgainofoxygen

isoxidation[1].(b) CO2+C→2CO [3]

15 Magnesiumismorereactivethaniron[1],somagnesiumreactsfirst[1].

Chapter 23 Rates of reaction 1 manganese(iv)oxide [1] 2 sulfur [1] 3 gassyringe [1] 4 2H2O2→2H2O+O2 [3] 5 rateincreases [1] 6 Asubstancethatincreasestherateofa

chemicalreaction[1]withoutbeingusedup[1]. 7 hydrogen [1] 8 sizeofsolidparticles/presenceofacatalyst [1] 9 changeinmassagainsttime[1];usingaconical

flaskonabalance[1];orchangeingasvolumeagainsttime[1];inagassyringe[1]

10 Hydrogenions/particlesmovefaster/havemoreenergy[1],sotherearemorecollisions[1]andmoresuccessfulcollisions/morecollisionswithhigherthanactivationenergy[1]inagivenperiodoftime[1];rateincreases[1]. [max.4]

11 (a) 80seconds [1](b) 80cm3 [1](c) 25seconds [1](d) startsat(0,0),remainshigherandlevels

offatthesamelevel [1](e) startsat(0,0),remainslowerandlevels

offatthesamelevel [1]

Chapter 24 Equilibrium1 H2+Br22HBr [3]2 temperature[1];pressure[1]

Chapter 25 Organic chemistry 1 (a) C2H6 [1]

(b) C2H4 [1](c) C4H10 [1](d) CH4 [1]

2 orange/brownsolutionchangestocolourless[1] 3 compoundscontainingonlycarbonand

hydrogen [1] 4 (a) propane [1]

(b) but-2-ene [1](c) propan-1-ol [1]

5 C2H5OH+3O2→2CO2+3H2O [3] 6 ethane [1] 7 fractionaldistillation [1] 8 2CH3COOH+Mg→(CH3COO)2Mg+H2 [3] 9 Afamilyoforganiccompoundswiththesame

generalformula[1],whichdifferbyaCH2unit[1].Theyshowagradationintheirphysicalproperties[1]andsimilarchemicalproperties[1]. [max.3]

10 (a) polythene [1](b) PVC [1]

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11 climatechange/risingsealevels/meltingofpolaricecaps/floodingoflow-lyingareas/globalwarming [3]

12 carbonmonoxide[1],soot[1]andwater[1]13 2C3H7COOH+Na2CO3→ 2C3H7COONa+CO2+H2O [3] sodiumbutanoate,carbondioxide,water [1]14 CnH2n+2 [1]

Chapter 26 Quantitative chemistry II 1 (a) 281 [1]

(b) 238 [1] 2 massofiron=100−27.6=72.4 [1] molesofFe=72.4/56=1.293 [1] molesofO=27.6/16=1.725 [1] simplestratio=3:4/Fe3O4 [1] 3 massofcopper=3.2g molesofcopper=3.2/64=0.05 [1] massofoxygen=0.8g molesofoxygen=0.8/16=0.05 [1] simplestratio=1:1/CuO [1] 4 CH2O [1] 5 molesofS=40/32=1.25 [1] molesofO=60/16=3.75 [1] simplestratio=1:3/SO3 [1] 6 (a) 122.612- 122.400 = 0.212g [1]

(b) 0.212/106=0.002 [1](c) 122.900- 122.612 = 0.288g [1](d) 0.288/18=0.016 [1](e) 0.016/0.002=8 [1]

7 atomeconomy=(massofdesiredproduct/totalmassofproducts)×100 massofdesiredproduct(2N2)=56 [1] totalmassofproducts=164 [1] atomeconomy=(56/164)×100=34.1% [1]

Chapter 27 Electrochemistry 1 decomposition(of a liquid electrolyte)usinga

directcurrentofelectricity [1] 2 red-brown/pungent[1]gas[1]evolved 3 2Cl−→Cl2+2e− [3] 4(a) positiveelectrode [1]

(b) negativeelectrode [1] 5 liquid/solutionthatconductselectricity[1]and

isdecomposedbyit[1] 6 unreactive[1];goodconductorofelectricity [1] 7 Ions[1]canmoveandcarrycharge [1] 8 bauxite [1] 9 lowersoperating temperature[1];increases

conductivity[1]10 carbon/graphite [1]11 Carbonreactswithoxygen[1],formingcarbon

dioxidegas[1].

or C+O2→CO2 [2]

12 Al3++3e−→Al [3]13 2O2−→O2+4e− [3]

Theoxideionloseselectrons[1]andthelossofelectronsisoxidation[1].

Chapter 28 Energy changes in chemistry 1 (a) givesoutheat [1]

(b) takesinheat [1] 2 Theminimumenergyneededforareactionto

occur [1] 3 (a) Exothermic,becausetheenergychangeis

negative. [1](b) +192kJ [1]

4 Theenergyrequiredtobreakthebondsinhydrogenandchlorine[1]isless[1]thantheenergyreleasedwhenbondsareformedinhydrogenchloride[1].

5 (a) activationenergy[1];reactionpathway[1];energychange[1]

(b) Endothermic,becausetheenergychangeispositive/productsareatahigherenergythanthereactants. [1]

6 exothermic=BandD[1];endothermic=AandC[1]

7 totalenergyusedtobreakbonds=(2×436)+496=1368kJ [1]

totalenergyreleasedwhenbondsform=4×463=1852kJ [1]

energychange=1368−1852=−484kJ [1] 8 (a) Theenergyrequiredtobreakthebondsin

hydrogenbromide[1]ismore[1]thantheenergyreleasedwhenbondsareformedinhydrogenandbromine[1].

(b) totalenergyusedtobreakbonds=2×362=724kJ [1]

totalenergyreleasedwhenbondsform=436+190=626kJ [1]

energychange=724−626=+98kJ [1](c) positiveenergychangesoendothermic [1]

9 (a) totalenergyusedtobreakbonds=916+(3×436)=2224kJ [1]

totalenergyreleasedwhenbondsform=6×386=2316kJ [1]

energychange=2224–2316=−92kJ [1](b) Exothermic,becauseenergychangeis

negative. [1]10 (a) 2C−C;12C−H[1];7O=O[1];8C=O[1];12

O−H[1](b) totalenergyusedtobreakbonds=(2×348)

+(12×412)+(7×496)=9112kJ [1]totalenergyreleasedwhenbondsform=(8×803)+(12×463)=11980kJ [1]

energychange=9112−11980=−2868kJ [1]

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Chapter 29 Gas chemistry 1 nitrogen[1] 2 (a) hydrogenperoxide[1]andmanganese(iv)

oxide[1](b) calciumcarbonate[1]andhydrochloric

acid[1](c) zinc/magnesium[1]andhydrochloric

acid[1] 3 (a) litsplint[1]pop[1]

(b) limewater[1]turnsfromcolourless[1]tomilky[1]

(c) glowingsplint[1]relights[1](d) Useaglassrod[1]dippedinconcentrated

hydrochloricacid[1];awhitesmoke[1]isobservedifammoniaispresent.

4 Theproductofcombustioniswater[1],whichisnon-polluting[1].

5 infireextinguishers[1];infizzydrinks[1] 6 2H2O2(aq)→2H2O(l)+O2(g) [4] 7 inmedicine[1];inwelding[1] 8 limewater [1] 9 Thestrongtriplecovalentbond/N≡N[1]

requiressubstantialenergytobreak[1].10 CO2+H2O→H2CO3 [2]11 (a) S+O2→SO2 [2]

(b) yellowsolidmeltstoaredliquid[1];blueflame[1];colourless/mistypungentgasproduced[1]

12 CaCO3+2HCl→CaCl2+CO2+H2O [3]13 manganese(iv)oxide [1]14 anytwofrom:colourless/odourless/low

solubilityinwater [2]15 A=conicalflask [1] B=deliverytube [1] C=gasjar [1] D=beehiveshelf [1]

Physics

Chapter 30 Motion1 (a)15meastofhisstartingposition

(b)15+30+30=75m

(c)Averagespeed=totaldistancetotaltime

= 75m25s

=3m/s

(d)Averagevelocity=totaldisplacementtotaltime

= 15m25s

=0.6m/sdueeast

2 (a)–0.4m/s2

(b)7.2m

Theessentialideain(a)isthatyouquoteandapplythecorrectequationforacceleration.Youmustrealisethattheinitialvelocityis2.4m/sandthefinalvelocityiszero.In(b)youneedtoapplythe

ideathattheareaunderthegraph(theareaofthetriangle)representsthedisplacement.Rememberalsotousethenumbersontheaxes(notyourruler!)tofindtheheightandwidthofthetriangle.3 (a)60m

(b)120m(c)40m

In(a)thefatherstartstherace15secondsafterhisson.Howfarfromthestartisthesonatthattime?In(b)whenthefatherovertakesthesonbotharethesamedistancefromthestart,sotheirgraphscross.In(c)lookbacktothefirstlineofthequestion–howlongistherace?Atwhattimedoesthefatherfinishtherace?Whereisthesonatthistime?Sohowfaristhesonfromthefinishatthistime?4 (a)36m

(b)24m(c)5m/s

In(a)thedistancetravelledistheareabetweenthegraphforcarAandthetimeaxis.Thisareaisfoundastheareaofatriangle12slongwithaverticalheightof6m/s

In(b)carBtravels60min12sbythemethodusedin(a).Tofindthedistancebetweenthecars,subtracttheanswerto(a)fromthisdistance.(60–36=24m)

In(c)averagevelocity=(u + v)

2=

0+102

=5m/s5 2m/s

Bcorrespondstotimet=50sanddistance=80m.

Ccorrespondstotimet=80sanddistance=140m.

SubtracttofindthedistanceBC:

140–80=60m

speed=distancetime

=60m30s

=2m/s

Chapter 31 Forces1 (a)F=ma

(b)(i) a=−8000N2000kg =−4m/s2

(ii)u=v−atsou=5−(−4×9)=5+36=41m/s

2 m= Fa

=30004

=750kg

a= Fm

= (3600–1725)750

=1875750

=2.5m/s2

3 Combinedmassofriderandbicycle,

m= Fa

= 1202

=60kg

Massofbicycle=60−53=7kg,sojustwithintheICUlimit.

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4 (a)W=m×g=70×10=700N(b)(i) massisunchanged,70kg

(ii)weightonMoon=m×g=70×1.6=112N(c)W=m×g 105.6=12×g

g= 105.612

=8.8N/kg

(d)Theunitsforgcanbem/s2orN/kg.Theyareequivalentunits.

5 (a)v=Dt

= 187525

=75m/s

(b)vmax=2×vaverage=2×75=150m/s(c)Theaveragevelocityis0.(d)Thetotaldisplacementiszeroand

averagevelocity= totaldisplacementtimetaken

(e)Considerthedownwardmotion. S=½at2

1875=½a×252=½a×625

a= 1875(½×625)

=6m/s2

6 (a)100000N(Thereisnoresultantforceifthetrainismovingataconstantspeed.)

(b)F–friction=ma 175000–100000=25000×a 75000=25000a a=3m/s2

7 P= FA

= (5500×10)0.14

=3.93×105Pa

8 F=P×A=5000×(15×2)=150000N9 (a)anticlockwisemomentsaboutpivot

=clockwisemomentsaboutpivot 600N×75cm=F×225cm

F=600 × 75225

=200N

(b)forcesverticallyup=forcesverticallydown 200+forcethroughpivot=600 forcethroughpivot=600–200=400N

10(a)moment=force×distancefrompivot=5N×40cm=200Ncmclockwise

(b)anticlockwisemomentsaboutpivot=clockwisemomentsaboutpivot

weight×25=5N×40cm

weight=20025

=8N

11Takingmomentsaboutthepivot,anticlockwisemoment=clockwisemoment.

150N×2m=F×3m,whichgivesF=100N forcesverticallyup=forcesverticallydown 100+forcethroughpivot=150 forcethroughpivot=50Nupwards

Chapter 32 Density and kinetic theory1 (a)Thedensityofamaterialisdefinedasthe

massperunitvolume.(b)Measuremass,M,ofbraceletonatop-pan

balance. Measurevolumeofwaterinhalf-filled

measuringcylinderbefore(V1)andafter(V2)braceletisimmersedinwater.

Subtracttworecordedvolumestoobtainbraceletvolume,V.

CalculatetheratioMV

tofindthedensity.

(c)D=MV

=46g

2.4cm3=19.2g/cm3

(d)Gold(itsdensityisnearestthatofthebracelet)

2 (a)V=l×b×h=1.8m×1.2m×0.1m=0.216m3

(b)D=MV

=520kg

0.216m3=2407.4kg/m3

sotheslabisdenseenoughforbridgeconstruction

3 (a)1m3=100cm×100cm×100cm=1000000cm3

(b)1m3aluminiumhasmass2.7g/cm3×1000000cm3=2700000g

(c)D=MV

=2700kg

1m3=2700kg/m3

4 (a)60g(readingwithnoliquidincylinder)(b)Densityofliquid=gradientofgraph

= (140–60)g100cm3

=0.8g/cm3

Sotheliquidisethanol,becauseitsdensityisalso0.8g/cm3

(c)Thegraphwouldpassthroughpoint(0cm3,60g)buthaveasmallergradient(thatisitwouldbebelowthelinealreadyonthegrid).

(d)Thelowerdensityshowsthatthespacingofthemoleculesiniceisgreaterthantheaveragespacinginwater.Thisisunusual.Studentsshouldbeawarethatthedensityofthesolidisusuallygreaterthanthatoftheliquid.

Chapter 33 Energy1 work=F×d=(100× 10)×5.5=5500J2 (a)W=F×d=60N×200m=12000J

(b)P=Wt

= 12000J(4×60)s

=50W

3 (a)efficiency=usefuloutputenergytotalinputenergy

= 840kJ1050kJ

=0.8

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(b)Energywastedassoundandheattransferredtothesurroundings(andlightinflame)

4 inputchemicalenergy=usefuloutputenergyefficiency

=140000kJ0.28

=500000kJ

5 energy=power×time=3600W×(3×60)s=648000J

6 (a)W=F×d=1000N×0.4m=400J

(b)efficiency=usefuloutputenergytotalinputenergy

= 400J1200J

=0.33

7 KE=½mv2=½×120×(3000)2=540000000J=540MJ

8 GPE=mgh 176=2×g×10

g=17620

=8.8,sotheplanetisVenus

9

Heightaboveground/m

Gravitationalpotentialenergy/J

Kineticenergy/J

Totalenergy/J

Speed/m/s

5.0 100 0 100 0

4.0 80 20 100 4.47

3.2 64 36 100 6.00

1.8 36 64 100 8.00

0.0 0 100 100 10.00

10(a)GPE=mgh 10=0.2×10×h

h=102

=5m

(b)NotalloftheKEisconvertedintoGPE. Someenergyislostasheatandsoundwhen

theballhitstheground.

Chapter 34 Atomic and nuclear physics1 Massofnitrogen-13

remaining/gTimeinhalf-lives

Timeinminutes

80 0 0

40 1 10

20 2 20

10 3 30

10gwouldremainafter30minutes.2 20gto10gtakes5.26yearsand10gto5gtakes

another5.26years

Totaltimetakenis10.52years.3 Fromthetablebelow,4half-livestake32

minutes. Eachhalf-life=

324

minutes=8minutes.

Thehalf-lifeofstrontium-93is8minutes.

%ofstrontium-93remaining

Timeinhalf-lives

Timeinminutes

100 0

50 1

25 2

12.5 3

6.25 4 32

4

ActivityinBq Timeinhalf-lives Timeinhours

2000 –1 –24

1000(startfromhere)

0 0

500 1 24

250 2 48

125 3 72

Activity24hoursbeforearrivalis2000Bq. Activity72hoursafterarrivalis125Bq.5 (a)

Particle Mass Charge Number Location

Electron 1/1840 –1 6 orbitingnucleus

Neutron 1 0 6 inthenucleus

Proton 1 +1 6 inthenucleus

(b)(i) Aradioactivesubstanceisonethatdecaysbytheemissionofalphaparticles,betaparticlesorgammaradiation.

(ii)Radoninanemitterofalphaparticles.Whilethealphaparticlesemittedinthelungsbyingestedradonhaveashortrange,theyareintenselyionisingandcancausecancer.

(iii)Isotopesareelementswiththesamenumberofprotons,butadifferentnumberofneutrons.

6 (a)(i) Bothnucleihave6protons.(ii)Carbon-12has6neutrons,whilecarbon-14

has8neutrons(b)Thenitrogenis

7N.Thebetaparticleis–1β14 0

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(c)(i) In6000yearstheactivityofasamplewillfalltohalfitsoriginalactivity.

(ii)In3half-livestheactivitywillhavefallentooneeighthofitsoriginalactivity,i.e.10disintegrationspersecond.Sothedecreaseis80–10=70disintegrationspersecond.

7 Anhour(60minutes)is5half-lives.Aftereachhalf-lifetheproportiondecayingisdecreasedbyhalf.Soafter5halflivestheproportionpresentis(½)5or1/32oftheoriginalamountofmaterial.

8 (a)XandZareisotopes(b)XandZbothhave16protons,butXhas

14neutronsandZhas17neutrons.9 (a)Nuclearfusionisthejoiningtogetheroftwo

lighthydrogennucleitocreateanewnucleusofhelium.Asaresultvastquantitiesofenergyareevolved.Itcanonlyoccurwhenthetemperaturereachesseveralmilliondegrees.ItoccursnaturallyintheSunandinotherstars.

(b)(i) Thereareseriousproblemswithourexistingenergyresources.Fossilfuelsarenon-renewable,theywilleventuallyrunoutandtheirusecontributesmuchtothegreenhouseeffectandclimatechange.Nuclearfusiondoesnotcontributetoclimatechange,hasalmostinexhaustiblesuppliesoffuel(isotopesofhydrogenfromseawater)anditswasteproductsposenoseriousproblemsofdisposal.

(ii)Therearethreemajorproblems:– achievingasufficientlyhightemperature

(around15milliondegrees)– containmentoftheplasmaforlong

enoughforfusiontooccur– achievingaplasmawithasufficiently

highnumberanddensityofparticlesforcollisionstobesuccessful.

(c)(i) ITERistheInternationalThermonuclearExperimentalReactor.ItisanexperimentalnuclearfusionreactorbeingbuiltinsouthernFranceinvolvingthecooperationofscientistsandengineersfrom35nations.

(ii)Atthemomentnosinglecountryhastheresourcestoresearchanddevelopthetechnologyneededtoachieveathermonuclearfusionreactorthatproducesanetenergybenefit(i.e.wegetmoreenergyoutthanwhatweputin).Andtheneedtosolvetheworld’sincreasingdemandforenergycannotbemetwithexistingresourcesforverylong.ITERprovidesaresearchanddevelopmentplatformthatmightbringforwardthedaywhenwehavecontrolledfusiontomeettheworld’sneeds.

Chapter 35 Waves1 (a)Frequency(orwavelengthorspeed)

(b)Frequency

2 frequency=14

=0.25Hz

wavelength=10m speedofthewave=f×λ =0.25×10=2.5m/s3 (a)Ultrasoundissoundatafrequencygreater

than20kHz.(b)Ultrasoundhasamuchhigherfrequencythan

humanspeech.(c)Differences:ultrasoundcannottravel

throughavacuum,allelectromagneticwavescantravelinavacuum;ultrasoundisalongitudinalwave,allelectromagneticwavesaretransverse.

4 (a)

Wavelength,λ/m 0.7 1.0 1.5 2.5 4.0

Frequency,f/Hz 460 320 210 130 80

1/λ 1.43 1.0 0.67 0.40 0.25

(b)Verticalaxislabelledf/Hz,horizontalaxislabelled1/λ.Scalechosentouseatleasthalfthegraphpaper.Pointsplottedtowithin1smallsquare.Lineofbestfitdrawnwitharuler.

(c)Gradientisapprox.320–330m/s(dependsonlineoffit).

(d)Gradientisspeedofsound.(e)At250Hz,graphshows1/λhasavalueof

about0.76–0.78,givingawavelengthofabout1.28to1.32m(dependsonlineoffit).

Chapter 36 Light1 Virtual,laterallyinverted,samesizeasobject,

samedistancebehindmirrorasobjectisinfrontofmirror.

2 (a,b)

63

63

6363

27

27 27

27

(c)TheincidentrayandtherayreflectedfromM2areparalleltoeachother.

3 (a)Inbothcasesthelightbendsbecauseitchangesspeedasitleavestheair.

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(b)Angleofincidenceinglass=60° Angleofrefractioninglass=34.5° Angleofincidenceinwater=60° Angleofrefractioninwater=40.6°(c)Lightbendsmoreasitentersglass.

4 (a)real,diminished,inverted(b)Converging(convex)lens(c)Principalfociarewheretheredandgreen

linescrossthehorizontalline.Theopticalcentreisatthecentreofthelens.

(d)PFis17smallsquaresfromcentreoflens,sof=1.7cm

(e)Magnification= 715

=0.46

5

Glass

A B

6 (a)Dispersion(b)Allcoloursinsunlightarerefractedbythe

glass,buteachcolourbendsbyaslightlydifferentamount.Sotheresultisthatthecoloursinthesunlightareallseparated.

(c)

redviolet

Chapter 37 Electricity1 (a)Conventionalcurrent

(b)Arrowsfromrighttoleft.(c)Electrons(d)0.4A(e)Q=I×t=0.6A×60s=36C

2 (a)IsolatedresistorhasresistanceR=0.0090.003

=3Ω

Resistanceofparallelnetwork=33

=1Ω

Totalresistance=1+3=4Ω(b)Eachresistoris3Ω(c)Currentineachparallelresistoristhesame

andequalto3mA3

=1mA

Currentinisolatedresistor=3mA(d)Voltageacrosseachresistorinparallel

network=IR=0.001A×3Ω=0.003V Voltageacrossisolatedresistor=9mV=0.009V

3 (a)Currentincircuit= VR

= 12(80+40)

= 12120

=0.1A

VoltageacrossR1,V1=IR1=0.1×80=8V(b)Assumption:theresistanceofthevoltmeter

itselfissolargethatittakesnegligiblecurrent.4

Switch EffectiveresistancebetweenXandY/Ω CommentA B

Open Open 12 Tworesistorsinseries:6+6=12Ω

Open Closed 9 Lowertworesistorsinparallelnetworkgive3Ω.Thisisinserieswithisolatedresistortogive9Ω

Closed Open 9 Uppertworesistorsinparallelnetworkgive3Ω.Thisisinserieswithisolatedresistortogive3+6=9Ω

Closed Closed 8 Threeparallelresistorsgive6

3=2Ω.

Thisisinserieswithisolatedresistortogive2+6=8Ω

Chapter 38 Electricity in the home1 (a)Thefuseprotectstheappliancebymelting

whentoomuchcurrentflows,whichdisconnectsthecircuit.

(b)Liveisbrown,neutralisblue,earthisgreenandyellowstripes.

(c)Theearthwireprotectstheuserbyprovidingalowresistancepathtoearthratherthanallowingcurrenttopassthroughtheuser’sbody.

(d)Doubleinsulatedappliancesrequireonlyliveandneutralwires.Theyhavenoearthwire.

2 (a)kilowatt-hour(kWh) (b)816unitsat15penceeachcosts

816×15pence=12240pence=£122.40

(c)Maximumnumberofunits=costinpencecostperunit

= 1224016

=765units.

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3 (a)Allmetalpartsarecontainedwithinaninsulatingplasticcase.

(b)Theusercannottouchanymetalpartoftheappliance,sohecannotgetanelectricshock.

(c)Evenifthefuseweretoblow,thelivewirewouldstillbeconnectedtotheappliance,makingitpotentiallydangerous.

4 (a)I= PV

=125240

=0.52A,soselectthenexthighest

currentasthefuse.Usea1Afuse. (b)NumberofkWh=numberofkW×timeinhours

=0.125kW×8hours=1kWh. Costof1kWh=costof1unit=16pence

Chapter 39 Magnetism and electromagnetism1 (a)Increasethecurrentorincreasethenumber

ofturnsperunitlengthofcoilorinsertasoftironrodintothecoil.

(b)Inaferrousmetalscrapyard,theelectromagnetisattachedtotheendofacableattachedtoacrane.Whenthecurrentisswitchedontheelectromagnetcanliftferrousmetal.Whenitisswitchedoff,theferrousmetalfalls.

(c)(i) N S

current

(ii)N S

2 (a)TherewillbeanattractiveforcebetweenendBandeachpoleofthemagnet.Themetalrodisnotabarmagnet,otherwisetherewouldbeattractionwhenoneendfacedthenorthpoleandrepulsionwhentheotherendfacedthenorthpole.Sinceitisnotmagnetised,therewillbeattractionbetweenBandeachpole.

(b)Themetalrodisnotmagnetised,butitisamagneticmaterial.Themostcommonsuchmaterialisiron.

3 (a)Aplottingcompassisatinymagnet,mountedonaspindlewithinatransparentcase.

(b)Placethebarmagnetatthecentreofasheetofwhitepaper.Placethecompassclosetothenorthpoleofthebarmagnet.Withapencildrawtwodotsonthepaper,oneateachendofthecompass.Movethecompassandsetitsothattheneedlepointstothelastdrawndot.(SeeFigure39.1onp.333.)Repeatandfinallyjointhedotstoshowthefieldline.Repeat,startingfromadifferentpointclosetotheNpole.

(c)SeeFigure39.2onp.333.4 (a)Analternatingcurrentisonethatchanges

sizeanddirectioninaregularrepetitiveway.Adirectcurrentisonewhichalwaysflowsinthesamedirection.

(b)

0

(iii)

(i)

(ii)

(c)(i) themainselectricalsupply(ii)abattery

5 (a)Fieldlineswithinthecoilarestraight,parallelandequallyspaced

Centralfieldlineextendsindefinitelytoleftandright

Allotherfieldlinesformloopsoutsidethecoil Fieldlinesnevercrossortouch Arrowsarelefttorightoutsidecoil,rightto

leftwithincoil(b)Theleftofthecoilisnorth(c)Increasecurrent(byusingastrongerbattery),

usemoreturnsonthecoil,insertasoftironrodintothecoil.

6 (a)Theneedlewoulddeflecttoonesideofthezeroandthenreturntothecentre.

(b)Theneedlewoulddeflecttotheothersideofthezeroandthenreturntothecentre.

(c)Electromagneticinduction(d)Insertanironrodbetweenthecoilsbefore

openingorclosingtheswitch.(e)Theresistorlimitsthecurrenttoprotectthe

ammeter.7 (a)VerticallydownthepaperfromX

(b)Fleming’sleft-handrule(c)FieldlinesNtoS,butcurvedandclose

togetherabovewire,curvedandfarapartbelowwire

(d)Useastrongermagnet8 (a)(i) Theprimarycoilhasmoreturnsandison

therightinFigure11.42;thesecondarycoilisontheleft

(ii) (soft)iron(iii)Toinducecurrentinthesecondarycoil,

thecurrentintheprimarycoilmustbechanging,asinana.c.supply.

(b)(i) Purpose:toincreasevoltageintransmissionlines,sothepowercanbetransmittedatalowercurrent.

16

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CCEA GCSE Science Double Award

Benefit:reducedcurrentintransmissionlinesmeanslessenergyislostasheat.

(ii)Ns

Np

=Vs

Vp

soNs

76100=

230175030

Ns=76100×230

175030=100turns

(iii)P=IV=5A×175030V=875150W=875.15kW(iv)I=P/V=875150/230=3805A

Chapter 40 Space physics1 (a)Gravity

(b)Hydrogenandhelium(c)Theyhavethesamelineabsorptionspectraas

hydrogenandheliumonEarth.(d)Nuclearfusion(e)Helium

2 (a)Toundergofusionnucleimustcollideandremainincontactforlongenoughforthemtoformanewnucleus.Beingpositivelycharged

theytendtorepeleachother.Thehightemperatureisessentialforthemtocollidewithenoughspeedthattheyfuse.

(b)Stellarstabilityrequirestheradiationpressuretoequalthegravitationalforce.AmoremassivestarhasmoregravitythanourSun.Forstabilitywerequiregreaterradiationpressure,sotherateatwhichfuelisusedmustbebigger.

(c)Massreductionperyear=(4×109)×(60×60×24×365)=1.26×1017kg

%reduction=(1.26×1017)

2×1030×100%=6.3×10−12%

3 asteroid,planet,ourSun,neutronstar,blackhole,galaxy

4 MilkyWay