sengkang chemistry 2024 prelim p4 p.pdf

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. …………………………………………………………………………………………… …………………………………………………………………………………………… ……………………………………………