a. All questions are compulsory. b. Section A: Q.no. 1 to 16 are

1/22

MaximumMarks:70

TimeAllowed:3hours

GeneralInstructions:

a. Allquestionsarecompulsory.

b. SectionA:Q.no.1to16areveryshortanswerquestions(objectivetype)andcarry1mark

each.

c. SectionB:Q.no.17to23areshortanswerquestionsandcarry2markseach.

d. SectionC:Q.no.24to30arelonganswerquestionsandcarry3markseach.

e. SectionD:Q.no.31to33arealsolonganswerquestionsandcarry5markseach.

f. Thereisnooverallchoice.Howeveraninternalchoicehasbeenprovidedintwo

questionsoftwomarks,twoquestionsofthreemarksandallthethreequestionsoffive

marksweightage.Youhavetoattemptonlyoneofthechoicesinsuchquestions.

g. Uselogtablesifnecessary,useofcalculatorsisnotallowed.

SectionA

1. Oxidationwithoutcleavageofsigmabondtakesplaceinalkenes:

PresenceofunsaturationinalkenesisdetectedusingBaeyer'sreagent.

AlkenesdecolourisepinkcolourofBaeyer'sreagent.InthepresenceofBaeyer's

reagent,synadditionof-OHgroupstakesplaceonbothcarbonsofthedoublebond.

Thenextreactioncanbegivenas,

Ozonolysisofalkenesgivesozonide,whichonfurtherhydrolysisgivesaldehyde

CBSE Class 11 Chemistry

Sample Paper 07 (2019-20)

2/22

and/orketone.

Answerthefollowingquestions:

i. Linearpolyenesonozonolysisgivetwomolesofacetaldehydeandonemoleof

propanedial.Linearpolyenewillbe________.

ii. Orthoxyleneonozonolysiswillgive________.

(a) and (b)

iii. CH2=CH2andCH3-CH=CH2bothwillgiveformaldehydeonozonolysis.(True/False)

iv. Productofozonolysisgivesinformationabout:

a. configuration

b. conformation

c. bothofthese

d. noneofthese

v. WhywouldBayer'sReagentisusedforthedetectionofthealkene?

2. Whyisenergyof1selectronlowerthan2selectron?

3. Na+hashighervalueofionizationenthalpythanNe,thoughbothhavesame

electronicconfiguration.Explainwhy?

4. At298K,Kpforthereaction is0.98.Predictwhetherthe

reactionisspontaneousornot.

5. WhyisGroup1elementsknownasthemostelectropositiveelement?

6. Namethefivedistinctzonesoftheatmosphere.

7. Theorderofreactivityoffollowingalcohols,

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I.

II.

III.

IV.

towardsconcentratedHClis:

a. I>III>II>IV

b. I>II>III>IV

c. IV>III>II>I

d. IV>III>I>II

8. Inwhichofthefollowingcompounds,anelementexhibitstwodifferentoxidation

states.

a.

b.

c.

d.

9. Gasespossesscharacteristiccriticaltemperaturewhichdependsuponthemagnitude

ofintermolecularforcesbetweentheparticles.Followingarethecritical

temperaturesofsomegases.Fromthedatawhatwouldbetheorderofliquefactionof

thesegases?Startwritingtheorderfromthegasliquefyingfirst.

Gases H2 He O2 N2

Critical

temperature

inKelvin

33.2 5.3 154.3 126

4/22

a.

b.

c.

d.

10. Whichofthefollowingarenotredoxreactions?

a)K4[Fe(CN)6]+H2SO4+H2O K2SO4+CO+FeSO4+(NH4)2SO4.

b) .

c) .

d)

a. c,d

b. b,d

c. bonly

d. a,b

11. Hybridisationinmethane ethene ethyne(C2H2)involvessandp

orbitals.Choosethecorrecthybridorbitalsintheoptionsgivenbelowfor

and, respectively

a.

b.

c.

d.

12. Assertion:Borondoesnotform ionwhile isknown.

Reason:Bdoesnothaved-orbitalsinvalenceshellwhileAIhasd-orbitalsinvalence

shell.

5/22

a. BothassertionandreasonareCORRECTandreasonistheCORRECTexplanationof

theassertion.

b. BothassertionandreasonareCORRECTbut,reasonisNOTTHECORRECT

explanationoftheassertion.

c. AssertionisCORRECTbut,reasonisINCORRECT.

d. AssertionisINCORRECTbut,reasonisCORRECT.

13. Assertion:EmpiricalformulaofglucoseisHCHO.

Reason:MolecularformulaofglucosewillalsobeequaltoHCHO.


theassertion.





14. Assertion:Asubstancewhichgetsreducedcanactasreducingagent.

Reason:Anoxidisingagentitselfgetsoxidised.


theassertion.




d. BothassertionandreasonareINCORRECT.

15. Assertion:TerminalalkynesonoxidationwithBayer'sreagentgiveamixtureof

carboxylicacidandCO2.

Reason:Terminalalkynesshowacidiccharacter.

6/22


theassertion.





16. Assertion:ThevalueforvanderWaal'sconstant'a'ishigherforammoniathanfor

nitrogen.

Reason:Intermolecularhydrogenbondingispresentinammonia.


theassertion.





SectionB

17. Howisbondorderrelatedtothestabilityofamolecule?

18. WhatistheoxidationnumberofFein[Fe(CO)5]?

19. Theatomicradiiofalkalineearthmetalsaresmallerthanthoseofthecorresponding

alkalimetals.Explainwhy?

20. Cyclobutaneislessreactivethancyclopropane.Justify.

21. Writetheexpressionfortheequilibriumconstantforthereaction:4NH3(g)+5O2(g)

4NO(g)+6H2O(g)

OR

7/22

WritethetypeofhybridisationinvolvedinCH4,C2H4andC2H2.

22. Describethemethod,whichcanbeusedtoseparatetwocompoundswithdifferent

solubilitiesinasolvent.

OR

Howareinternalenergychange,freeenergychangeandentropychangearerelated

tooneanother?

23. Theboilingpointofalkanesshowsasteadyincreasewithanincreaseinmolecular

mass.Why?

SectionC

24. Theenthalpyofvaporisationofliquiddiethylether(C2H5)2Ois26.0kJmol-1atits

boilingpoint(35.0°C).Calculate S°fortheconversionof

i. liquidtovapourand

ii. vapourtoliquidat35°C.

25. i. Whyamoleculeismorestableintermsofenergythantheuncombinedatoms?

ii. Whysodiumchloridedoesnotconductelectricityinasolid-statebutdoessointhe

moltenstate?

iii. WhyH2OisliquidwhileH2Sisagasatordinarytemperature?

OR

Whatisthemaximumconcentrationofequimolarsolutionsofferroussulphateand

sodiumsulphidesothatwhenmixedinequalvolumes,thereisnoprecipitationof

ironsulphide?(Forironsulphide, .

26. Justifythatthefollowingreactionsareredoxreactions:

i. CuO+H2(g) Cu(s)+H2O(g)

ii. Fe2O3(s)+3CO(g) 2Fe(s)+3CO2(g)

iii. 4BCl3(g)+3LiAlH4(s) 2B2H6(g)+3LiCl(s)+3AlCl3(s)

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27. AnalysisshowsthatametaloxidehastheempiricalformulaM0.96O1.00Calculatethe

percentageofM2+andM3+ionsinthecrystal?

28. Chlorineispreparedinthelaboratorybytreatingmanganesedioxide(MnO2)with

aqueoushydrochloricacidgivenreaction,

+MnCI2(aq)+CI2(g)

CalculatehowmanygramofHCIreactswith5.0gofmanganesedioxide?

29. Theamountofenergyreleasedwhen atomsofchlorineinvaporstateare

convertedtoCl-ionsaccordingtotheequation,

CalculatetheelectrongainenthalpyofthechlorineatomintermsofkJmol-1andeV

peratom.

OR

ShowbyachemicalreactionwithwaterthatNa2OisabasicoxideandCl2O7,isan

acidicoxide.

30. Discussthewaterpollutioncausedbyindustrialwater.

SectionD

31. TheMn3+ionisunstableinsolutionandundergoesdisproportionationtogiveMn2+,

MnO2andH+ion.

Writeabalancedionicequationforthereaction.

OR

Completethefollowingchemicalreactions.

i. PbS(s)+H2O2(aq)

ii.

iii. CaO(s)+H2O(l)

iv. AlCl3(g)+H2O(l)

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v. Ca3N2(s)+H2O(l)

Classifytheaboveinto(a)hydrolysis,(b)redoxreactions.

32. i. Drawthetwogeometricalisomersofbut2-en-1,4-dioicacid.Whichofthesewill

haveahigherdipolemoment?

ii. Howmanyisomersarepossibleformonosubstitutedanddisubstitutedbenzene?

OR

i. Thereductiveozonolysisofanalkenegavebutanoneandpropanal.Writethe

structureofalkeneanditsIUPACname.

ii. OzonolysisofanalkeneXfollowedbydecompositionwithwaterandareducing

agentgaveamixtureoftwoisomersoftheformulaC3H6O.Giventhestructureof

thealkeneanditsIUPACname.

33. i. Theradiusofthefourthorbitinahydrogenatomis0.85nm.Calculatethevelocity

oftheelectroninthisorbit(massofelectron=9.1 10-31kg).

ii. ThewavelengthoffirstspectrallineintheBalmerseriesis6561 .Calculatethe

wavelengthofthesecondspectrallineintheBalmerseries.

OR

Thefollowingdatawereobtainedwhendinitrogenanddioxygenreacttogetherto

formdifferentcompounds:

Massofdinitrogen Massofdioxygen

14g 16g

14g 32g

28g 32g

28g 80g

i. Whichlawofchemicalcombinationisobeyedbytheaboveexperimentaldata?

Giveitsstatement.

ii. Fillintheblanksinthefollowingconversations:

a. 1km=________mm=________pm

10/22

b. 1mg=________kg=________ng

c. 1mL=________L=________dm3

11/22

Solution

SectionA

1. i. LinearpolyenewillbeAlkadiene.

ii. Orthoxyleneonozonolysiswillgive

iii. False,becauseonlyCH2=CH2willgiveformaldehydeonozonolysis.

iv. Noneofthese

v. Bayer'sreagentdetectsthepresenceofunsaturationinalkenes.Hence,itisused

forthedetectionofthealkene.

2. Weknowthat,Energyofanelectronisinverselyproportionaltoprincipalquantum

number.

1s(n=1)electronbeingclosetothenucleusexperiencesmoreforceofattractionthan

2s(n=2)electronwhichisawayfromthenucleus.

3. BothNa+andNebothhas10electronsbutNa+having,11protonsinitsnucleusbut

Nehas10protons.There,IncaseofNa+effectivenuclearchargeishighandthus

Na+hasgreaterionisationenthalpythanNe.

4. Given,At298K, .

Weknowthat,

Accordingtothequestion,Kp=0.98.

As,Kp<1, willbepositive.

Hence,thereactionisnon-spontaneous.

5. Thelooselyhelds-electronintheoutermostvalenceshelloftheseelementsmakes

themthemostelectropositivemetals.Theyreadilyloseanelectrontogive

monovalentM+ions.

CBSE Class 11 Chemistry

Sample Paper 07 (2019-20)

12/22

6. Thefivedistinctzonesoftheatmosphereareasfollows:

i. Troposphere

ii. Stratosphere

iii. Mesosphere

iv. Ionosphere

v. Exosphere

7. (d)IV>III>I>II

Explanation:IV>III>I>II

8. (a) Explanation:

NH4+NO3

-.InNH4+

Nis-3and

NO3-,Nis+5.

9. (c)

Explanation:

Tc= Rb.AsTcincreases‘a’increasesmeansforceofattractionbetweenmolecules

alsoincreasehenceliquificationincreases.

Inortherwords,morethecriticaltemperaturemorewillbetheeaseofliquification.

10. (d)a,b

Explanation:a)K4[Fe(CN)6]+H2SO4+H2OK2SO4+CO+FeSO4+(NH4)2SO4

b)

Since,oxidationnumberofeachelementdoesnotchangeinthesereactions,sothese

arenotredoxreactions.

11. (b)

Explanation:InmethaneCis hybridisedbecauseof3sigmabondformation.

WhileinethaneboththeCare hybridised,andinethyneboththeCaresp

hybridised.

12. (a)BothassertionandreasonareCORRECTandreasonistheCORRECTexplanationof

theassertion.

13/22

Explanation:BothassertionandreasonareCORRECTandreasonistheCORRECT


13. (c)AssertionisCORRECTbut,reasonisINCORRECT.

Explanation:AssertionisCORRECTbut,reasonisINCORRECT.

14. (d)BothassertionandreasonareINCORRECT.

Explanation:BothassertionandreasonareINCORRECT.

15. (b)BothassertionandreasonareCORRECTbut,reasonisNOTTHECORRECT


Explanation:BothassertionandreasonareCORRECTbut,reasonisNOTTHE

CORRECTexplanationoftheassertion.

16. (a)BothassertionandreasonareCORRECTandreasonistheCORRECTexplanationof

theassertion.

Explanation:BothassertionandreasonareCORRECTandreasonistheCORRECT


SectionB

17. Bondorder:-Numberofbondsbetweentwoatomsiscalledbondorder.Morethe

bondsbetweenatomsmorewillbetheDissociationEnergy&morewillbethe

stability.

FormulatofindBondorder=NB-NA/2

Bondorderdirectlyproportionaltostabilityofmoleculesanddissociationenergyand

inverselyproportionaltobondlength

whereNB=NumberoftheelectroninbondingMolecularOrbits

NA=NumberoftheelectroninantibondingMolecularOrbits

18. TheoxidationnumberofFeinFe(CO)5isZero

Explanation/Calculations:

Fe(CO)5isIroncarbonyl,containingFeasthecentralatomwhichislinkedwitha

neutralgroup/ligandCO(iecarbonylgroup)

Sincethecarbonylgroupitselfisamoleculeitsoxidationnumber=0

Now,lettheoxidationnumberofFeinFe(CO)5berepresentedbyx,then

14/22

Thus,theoxidationnumberofFeinFe(CO)5isZero

19. Aswemovefromlefttorightinmodernperiodictable,nuclearchargeincreases

progressivelybyoneunit.Therefore,theatomicandionicradiiofthealkalineearth

metalsaresmallerthanthoseofthecorrespondingalkalimetalsinthesameperiod.

20. Incyclobutanemolecule,theC-C-Cbondangleis900whileitis600incyclopropane.

Thus,thedeviationfromthetetrahedralbondangle(109028')incyclobutaneisless

thanincyclopropane.Therefore,cyclobutanehaslessbondstrainascomparedto

cyclopropaneandthus,cyclobutaneislessreactiveascomparedtocyclopropane.

21. Thegivenreactionis4NH3(g)+5O2(g) 4NO(g)+6H2O(g).

Henceequilibriumconstant,

OR

Hybridisation=sigmabond+lonepair

IfNo.is4thensp3,IfNo.is3thensp2,IfNo.is2thensp

CH4=Sp3C2H4=Sp

2C2H2=Sp

22. Fractionalcrystallizationisusedforthispurpose.Ahotsaturatedsolutionofthese

twocompoundsisallowedtocool,thelesssolublecompoundcrystallizesoutwhile

themoresolubleremainsinthesolution.Thecrystalareseparatedfromthemother

liquorandthemotherliquorisagainconcentratedandthehotsolutionagainallowed

tocoolwhenthecrystalsofthesecondcompoundareobtained.Theseareagain

filteredanddried.

OR

Therelationbetweeninternalenergychange,freeenergychangeandentropy

changecanbeshowanas:

∆G=∆H-T∆S.(AtConstantTemperature)

15/22

23. Withtheincreaseinmolecularweightorthemolecularsizeofthemolecule,the

surfaceareaofthemoleculeincreases.Duetowhichtheextentoftheintermolecular

Vanderwallforcesincreaseswhichcausestheincreaseintheboilingpointofalkanes.

SectionC

24. i. Weknowthat,

Accordingtothequestion,

So,

ii. Theconversionofvapourintoliquidiscondensation.

Theenthalpyofcondensationisnegativeofenthalpyofvaporisation.

Weknowthat,

=-84.4JK-1mol-1

25. i. Whentheatomscombinetogethertoformamolecule,thereisalwaystherelease

ofenergy.Thus,thepotentialenergyofamoleculeislessthanthatofuncombined

atomsandtherefore,themoleculeismorestable.

ii. Solidsodiumchloridehasacrystallinestructureinwhichtheionsarenotfreeto

move.Theionsbecomemobilewhenitisinamoltenstateandthus,theelectricity

canbeconducted.

iii. Oxygenhasahighelectronegativitythansulphur.Asaresult,H2Oformshydrogen

bonding.Consequently,moleculesofwatercomenearertoeachotherthrough

hydrogenbonding.Thisresultishigherboilingpointofwaterandhenceitisa

liquid.

OR

SupposetheconcentrationofeachofFeSO4andNa2SisxmolL-1.Thenaftermixing

equalvolumes,

[FeSO4]=[Na2S] ,i.e.

KspforFeS=[Fe2+][S2-]i.e. [Since,equimolarsolutions

aretobemixed,henceonmixingconcentrationishalved.]

or

16/22

26. Thegivenequationsfordifferentreactionsare:

i.

Asperaboveequation,itisnotedthat.

a. anatomofoxygen(O)isremovedfromCuO,

itisreducedtoCu,while

b. OisaddedtoH2toformH2O

itisoxidized.

Further,

Oxidationnumber.ofCudecreasesfrom+2inCuOto0inCu,

oxidationnumberofHincreasesfrom0inH2to+1inH2O.

CuOisreducedtoCubutH2isoxidizedtoH2O.

Thus,thereactionisaredoxreaction.

ii.

Intheaboveequationforreaction,itisseenthat

a. TheoxidationnumberofFedecreasesfrom+3inFe2O3to0inFe,and

oxidationnumberofCincreasesfrom+2inCOto+4inCO2.

Further,

oxygenisremovedfromFe2O3,and

addedtoCOtoformCO2

therefore,Fe2O3isreducedwhileCOisoxidized.

Thus,thegivenreactionisaredoxreaction.

iii. Similarly,inthegivenequation,

4B+3Cl-13(g)+3Li+1Al+3H-1

4(s) 2B-32H-16(g)+3LI

+1Cl-1(s)+3Al+3Cl-13

OxidationnumberofBdecreasesfrom+3inBCl3to-3inB2H6

while,

oxidationnumberofHincreasesfrom-1inLiAlH4to+1inB2H6.

Therefore,BCl3isreducedand

LiAlH4isoxidized.

Further,itisnotedthat,

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HisaddedtoBformingB2H6fromBCl3butisremovedfromLiAlH4,

therefore,

BCl3isreducedwhileLiAlH4isoxidised.

Thus,

theredoxnatureofabovereactionisjustfied.

27. LetthenumberofM2+ion=x

Then,thenumberofM3+ionwillbe=(0.96-x)

Totalno.ofcations=2x+3(0.96-x)=2x+2.88-3x

=-x+2.88

No.ofanionsO2-=-2x1=-2

No.ofcations=No.ofanions

-x+2.88=2

-x=-2.88+2

-x=-0.88

x=0.88

PercentageofM2+ion =91.67%

PercentageofM3+= =8.33%

28. Thegivenchemicalequationis:

Itisclearfrombalancedchemicalequation,

87gofMnO2reactswith146gHCI

Therefore,5gofMnO2willreactwith= =8.4gHCl.

29. TheequationofconversionofCl(g)intoCl-is:.

Theeamountenergyreleasedwhen1-mole chlorineareconverted

intoCl-ionsaccordingtotheaboveoftheequationwillbe

18/22

Now1eV/atom

Electrongainenthalpyofchlorine

OR

Na2Oreactswithwatertoformsodiumoxidewhichturnsredlitmusblue.

Therefore,Na2Oisabasicoxides.

Incontrast,Cl2O7reactswithwatertoformperchloricacidwhichturnsbluelitmus

red.

Therefore,Cl2O7isanacidicoxide.

30. Thecompoundsoflead,mercury,Cd,Ni,Co,Znetcwhicharetheproductsof

chemicalreactions,carriedintheindustrialunits,pollutewatertoalargeextentand

areresponsibleformanydiseases.Mercuryleadstominimatadisease,leadpoisoning

leadstomanydeformities.Inaddition,thesesubstancesaddstothesoiland

harmfullyaffecttheplantgrowthandthewholesoilbioticsystem.Bothgroundwater

andwaterbodiesarepollutedduetochemicalreactionsknownasleaching.

SectionD

31. Thefollowingstepsareprocessedtowritethedesiredbalancedionicequation,

Theskeletalequationis,

Mn3+(aq) Mn2+(aq)+MnO2+H+(aq)

Identifytheoxidationandreductionofhalfequationsfromtheskeletalequation

Oxidationhalf-equation:

Balancinghalfequationsinthefollowingsteps,

19/22

i. balanceO.N.byaddingelectronsatthesuitableside(ie.RHS)

MnO2(s)+e-

ii. Balancechargebyadding4H+ionsonRHS,

(aq) MnO2(s)+4H+(aq)+e-

iii. BalanceOatomsbyadding2H2OonasideoppositetothatofH+ion:

(aq)+2H2O(l) MnO2(s)+4H+(aq)+e-(i)

Reductionhalfequation:

BalanceO.N.byaddingelectronsonthesuitableside(ie.LHS)

Mn3+(aq)+e- Mn2+(aq)(ii)

AddingEq.(i)andEq.(ii),thebalancedequationfortheionicreactionisobtained

asunder,

2Mn3+(aq)+2H2O(l) MnO2(s)+Mn2+(aq)+4H+(aq)

OR

i.

ii.

iii.

iv.

v.

a. (iii)and(v)arehydrolysisreactionsasgivenioniccompoundsgethydrolysed

inwater.

b. (iv)isahydrationreaction.

c. (i)and(ii)areredoxreactionsasin(i)H2O2actsanoxidisingagentwhereasin

(ii)itactsasareducingagent

32. Thetwogeometricalisomersofbut2-en-1,4-dioicacidareasfollow:

20/22

Cisisomerswillhaveahigherdipolemoment.

i. Thereisonemonosubstitutedbenzeneas

Therearethreedisubstitutedbenzenes:

OR

i. Theproductsofozonolysisare:

Thealkenewillbe(removeoxygenatomsandmakeadoublebondbetweenthe

carbonylcarbonatoms).

IUPACname:

ii. ThetwoisomersofthemolecularformulaC3H6Oare:

Thealkeneis

21/22

IUPACname:2-Methylpent-2-ene

33. i. FromBohr'spostulate,theangularmomentum(mvr)isgivenas:

mvr= orv=

n=4,m=9.1 10-31kg,r=0.85 10-9m

v=

=5.45 105ms-1

ii. AccordingtoRydbergequation,

=R

Forfirstlineinbalmerseries,n1=2,n2=3

=R =R ...(i)

Forsecondlineinbalmerseries,n1=2,n2=4

=R =R .....(ii)

Dividingeq.(i)by(ii),

=

= =4860

OR

i. Fixingthemassofdinitrogenas14g,themassesofdioxygencombinedwillbe

or

16:32:16:40

2:4:2:5

Thisisasimplewhole-numberratioandhence,thedataillustratethelawof

multipleproportions.

Thelawofmultipleproportionsstatesthatwhentwoelementscombinetoform

twoormorethantwocompounds,thenthemassofoneoftheelementswhich

combinewithafixedmassoftheotherbearasimplewhole-numberratio.

ii.

a. 1km=1km =106m

22/22

1km=1km =1015pm

Correctanswer:106,1015

b. 1mg=1mg =10-6kg

1mg=1mg =106ng

Correctanswer:10-6,106

c. 1mL=1mL =10-3L

1mL=1cm3 =10-3dm3

Correctanswer:10-3,10-3

Documents

a. All questions are compulsory. b. Section A: Q.no. 1 to 16 are