Exam practice answersresources.hoddereducation.co.uk/files/he/myrevisionnotes/0404519_MRN... ·...
Transcript of Exam practice answersresources.hoddereducation.co.uk/files/he/myrevisionnotes/0404519_MRN... ·...
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]
2
Exa
mp
ract
ice
answ
ers
CCEA GCSE Science Double Award
(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
3
Exa
mp
ract
ice
answ
ers
CCEA GCSE Science Double Award
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]
4
Exa
mp
ract
ice
answ
ers
CCEA GCSE Science Double Award
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]
5
Exa
mp
ract
ice
answ
ers
CCEA GCSE Science Double Award
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]
6
Exa
mp
ract
ice
answ
ers
CCEA GCSE Science Double Award
(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]
7
Exa
mp
ract
ice
answ
ers
CCEA GCSE Science Double Award
(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]
8
Exa
mp
ract
ice
answ
ers
CCEA GCSE Science Double Award
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]
9
Exa
mp
ract
ice
answ
ers
CCEA GCSE Science Double Award
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]
10
Exa
mp
ract
ice
answ
ers
CCEA GCSE Science Double Award
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.
11
Exa
mp
ract
ice
answ
ers
CCEA GCSE Science Double Award
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
12
Exa
mp
ract
ice
answ
ers
CCEA GCSE Science Double Award
(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
13
Exa
mp
ract
ice
answ
ers
CCEA GCSE Science Double Award
(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.
14
Exa
mp
ract
ice
answ
ers
CCEA GCSE Science Double Award
(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.
15
Exa
mp
ract
ice
answ
ers
CCEA GCSE Science Double Award
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
Exa
mp
ract
ice
answ
ers
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