sengkang chemistry 2024 prelim p4 p

14 NameandIndexNumber: () Class: SENGKANGSECONDARYSCHOOL 2024PRELIMINARYEXAMINATION SCIENCE(CHEMISTRY)5105/04Secondary4Normal(Academic)6 August2024Paper4Paper3and4:1hour15minutes READTHESEINSTRUCTIONSFIRST Writeyourindexnumberandnameonalltheworkyouhandin. Writeindarkblueorblackpenonbothsidesofthepaper. Youmayuseasoftpencilforanydiagrams,graphsorroughworking. Donotusestaples,paperclips,highlighters,glueorcorrectionfluid. SectionA Answerallquestions. Writeyouranswersinthespacesprovided. SectionB Answeronequestion. Writeyouranswersinthespacesprovided. Theuseofanapprovedscientificcalculatorisexpected,whereappropriate. Incalculations,youshouldshowallthestepsinyourworking,givingyouranswerateachstage. Youareadvisedtospendnolongerthan30minutesonPaper3. YoumayproceedtoanswerPaper4assoonasyouhavecompletedPaper3. AcopyofthePeriodicTableisprintedonpage14. AttheendoftheexaminationhandinyouranswerstoPaper3andPaper4separately. Thenumberofmarksisgiveninbrackets[]attheendofeachquestionorpartquestion. ForExaminer’suse SectionA /22 SectionB /8 Marks Awarded /30 Thisdocumentconsistsof13printedpagesand1blankpage. Donotturnoverthepageuntilyouaretoldtodoso. 2

SectionA[22marks] Answerallquestions. 1Theformulaeofsomeelementsandcompoundsarelisted. Cl2CO2K NONaClZnO Completethesentencesbelow,choosingyouranswersfromtheabovelist. Eachelementorcompoundmaybeusedonce,morethanonceornotat all.Identifytheelementorcompoundthat: (a)isadiatomicmolecule, ………………………………………………………………………………………… …(b)reactswithbothdilutehydrochloricacidandsodiumhydroxide, ………………………………………………………………………………………… …(c)displacesiodinefromsodiumiodide, ………………………………………………………………………………………… …(d)dissolvesinwatertoformasolutionwithpHlessthanseven. ……………………………………………………………………………………………[3] [Total:3] [Turnover 3

2(a)Table2.1showsdataonthreealloysmadefromtin,copperandsilver. Table2.1 alloy1alloy2alloy3 tincontent/% 95.5 96.5 99.0 coppercontent/%0.7 0.5 0.7 silvercontent/%3.8 3.0 0.3 meltingpoint/°C217 220 227 UsethedatainTable2.1todescribetherelationshipbetweenthesilvercontentand themeltingpoint. …………………………………………………………………………………………… ……………………………………………………………………………………………[1] (b)Fig.2.2showsfourdifferentmetalsA,B,CandDreactingwithcoldwater. D B cold water AC Fig.2.2 (i)UsetheobservationsinFig.2.2tosuggestanorderofreactivityofthesemetals. mostreactive…………. …………. …………. leastreactive………….[1] (ii)Drawa‘dotandcross’diagramtoshowthebondingofthegasevolvedwhen metalBreactswithcoldwater.

[1] [Turnover 4 (c)Somemetalsareextractedfromtheiroresbyheatingwithcarbon. Othermetalsareextractedfromtheiroresbyelectrolysis. Fig.2.3showstheorderofreactivityoffivemetals,comparedtocarbon. mostreactiveleastreactive potassium sodium calcium [carbon] zinc extractedbyheating withcarboncopper Fig.2.3 Astudentmakesthisstatement: ‘TheinformationinFig.2.3showsthatallGroup1metalsareextractedby electrolysis.’ UseinformationfromFig.2.3toexplainwhythisstatementisonlypartlycorrect. …………………………………………………………………………………………… …………………………………………………………………………………………… ……………………………………………………………………………………………[2] [Total:5]

[Turnover 5 3(a)Carbondioxide,CO2,isagasfoundintheEarth’satmosphere.Theconcentrationof carbondioxideintheEarth’satmosphereismeasuredinpartspermillion. Fig.3.1showsthechangeincarbondioxideconcentrationintheEarth’satmosphere overthelast575millionyears. CO2 concentration /parts permillion currentCO2concentration millionsofyearsago Fig.3.1 (i)Carbondioxideconcentrationwasatitshighestabout530millionyearsago.

Statethevalueoftheconcentrationofcarbondioxide530millionyearsago. concentrationofcarbondioxide=.....................partspermillion[1] (ii)Astudentsays,‘Carbondioxideconcentrationwasalwaysmuchhigherinthe pastthanitistoday.’ Doesthegraphsupportthisstatement?Usevaluesfromthegraphtoexplain youranswer. …………………………………………………………………………………... …………………………………………………………………………………...[2] [Turnover 6 (b)Fig.3.2showstheamountofoilburnedandthechangeintheEarth’stemperature betweentheyears1850and2010. temperatureoil changeinEarth’s temperature yearFig.3.2 thousand millionbarrelsofoil burnedperyear

Itissuggestedthattheremightbearelationshipbetweenthetotalamountofoil burnedperyearandthechangeinEarth’stemperature. ExplainhowtheinformationinFig.3.2supportsthisidea. …………………………………………………………………………………………… ……………………………………………………………………………………………[1] (c)Somescientistsfearthatclimatechangemaycauseotherlong-termenvironmental problems. Describetwootherlong-termenvironmentalproblemscausedbyclimatechange.1. ………………………………………………………………………………………... ……………………………………………………………………………………………2. ………………………………………………………………………………………... ……………………………………………………………………………………………[2] [Total:6] [Turnover 7 4‘Tumsoothe’isamedicinethatcuresindigestion.Itcontains‘sodiumbicarbonate’,NaHCO3. Astudentusestheapparatus,showninFig.4.1,tostudythereactionbetweendilute hydrochloricacidandTumsoothe. rubberbung 300.0gTumsoothe

Theequationforthereactionis dilute hydrochloricacid weighingmachine Fig.4.1 NaHCO3(aq)+HCl(aq)→NaCl(aq)+H2O(l)+CO2(g) (a)ThestudentmakestwomistakesinFig.4.1. (i)Fig.4.2showsthetopviewoftheweighingmachinethatwasusedinFig.4.1. 00.0kg Fig.4.2 Onemistakeistheuseofweighingmachinetomeasurethemass. Explainhowthismistakewillaffecttheexperiment. …………………………………………………………………………………... …………………………………………………………………………………...[1](ii) Identifythesecondmistakeandsuggesthowthismistakewouldbecorrected. mistake…………………………………………………………………………correction ……………………………………………………………………… …………………………………………………………………………………...[2] [Turnover 8 (b)ThemistakesinFig.4.1arecorrected.Themassismeasuredevery10seconds,as showninTable4.3. Table4.3 time/s mass/g

0 300.0 10 298.0 20 296.0 30 294.5 40 293.5 50 292.5 60 292.0 (i)UsingTable4.3,plotagraphofmassagainsttimeontheaxesbelow.Draw acurvedlineofbestfittakingintoaccountallyourplottedpoints.mass/g time/s [2] (ii)Usingyourgraph,estimatethemassoftheconicalflaskat100seconds.mass at100s=…………………g[1] [Turnover 9 (iii)UsingthedatainTable4.3,calculatethemassofcarbondioxidegasproduced at60seconds.

massofcarbondioxidegas=…………………g[1] (iv)Usingyouranswerin(b)(iii),calculatetheamount,inmoles,ofcarbondioxide gasproducedat60seconds. amountofcarbondioxidegas=…………………[1] [Total:8] [Turnover 10 SectionB[8marks]