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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
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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.
a. BothassertionandreasonareCORRECTandreasonistheCORRECTexplanationof
theassertion.
b. BothassertionandreasonareCORRECTbut,reasonisNOTTHECORRECT
explanationoftheassertion.
c. AssertionisCORRECTbut,reasonisINCORRECT.
d. AssertionisINCORRECTbut,reasonisCORRECT.
14. Assertion:Asubstancewhichgetsreducedcanactasreducingagent.
Reason:Anoxidisingagentitselfgetsoxidised.
a. BothassertionandreasonareCORRECTandreasonistheCORRECTexplanationof
theassertion.
b. BothassertionandreasonareCORRECTbut,reasonisNOTTHECORRECT
explanationoftheassertion.
c. AssertionisCORRECTbut,reasonisINCORRECT.
d. BothassertionandreasonareINCORRECT.
15. Assertion:TerminalalkynesonoxidationwithBayer'sreagentgiveamixtureof
carboxylicacidandCO2.
Reason:Terminalalkynesshowacidiccharacter.
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a. BothassertionandreasonareCORRECTandreasonistheCORRECTexplanationof
theassertion.
b. BothassertionandreasonareCORRECTbut,reasonisNOTTHECORRECT
explanationoftheassertion.
c. AssertionisCORRECTbut,reasonisINCORRECT.
d. AssertionisINCORRECTbut,reasonisCORRECT.
16. Assertion:ThevalueforvanderWaal'sconstant'a'ishigherforammoniathanfor
nitrogen.
Reason:Intermolecularhydrogenbondingispresentinammonia.
a. BothassertionandreasonareCORRECTandreasonistheCORRECTexplanationof
theassertion.
b. BothassertionandreasonareCORRECTbut,reasonisNOTTHECORRECT
explanationoftheassertion.
c. AssertionisCORRECTbut,reasonisINCORRECT.
d. AssertionisINCORRECTbut,reasonisCORRECT.
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
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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
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
explanationoftheassertion.
13. (c)AssertionisCORRECTbut,reasonisINCORRECT.
Explanation:AssertionisCORRECTbut,reasonisINCORRECT.
14. (d)BothassertionandreasonareINCORRECT.
Explanation:BothassertionandreasonareINCORRECT.
15. (b)BothassertionandreasonareCORRECTbut,reasonisNOTTHECORRECT
explanationoftheassertion.
Explanation:BothassertionandreasonareCORRECTbut,reasonisNOTTHE
CORRECTexplanationoftheassertion.
16. (a)BothassertionandreasonareCORRECTandreasonistheCORRECTexplanationof
theassertion.
Explanation:BothassertionandreasonareCORRECTandreasonistheCORRECT
explanationoftheassertion.
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
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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,
17/22
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,
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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
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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
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