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CBSEClass10Science

SamplePaper01(2019-20)

MaximumMarks:80

TimeAllowed:3hours

GeneralInstructions:

i. Thequestionpapercomprisesthreesections–A,BandC.Attemptallthesections.

ii. Allquestionsarecompulsory.

iii. Internalchoiceisgivenineachsection.

iv. AllquestionsinSectionAareone-markquestionscomprisingMCQ,VSAtypeand

assertion-reasontypequestions.Theyaretobeansweredinonewordorinonesentence.

v. AllquestionsinSectionBarethree-mark,short-answertypequestions.Thesearetobe

answeredinabout50-60wordseach.

vi. AllquestionsinSectionCarefive-mark,long-answertypequestions.Thesearetobe

answeredinabout80–90wordseach.

vii. Thisquestionpaperconsistsofatotalof30questions.

SectionA

1. Writetheformulaandthenbalancethefollowingequation.

Ferroussulphate+Sodiumhydroxide→Ferroushydroxide+Sodiumsulphate

2. IntheModernPeriodicTable,calcium(atomicnumber20)issurroundedbyelements

withatomicnumbers12,19,21and38.Whichofthesehavephysicalandchemical

propertiesresemblingcalcium?

3. Answerthequestionsthatfollowonthebasisofyourunderstandingofthe

followingparagraphandtherelatedstudiedconcepts:

Inordertoproducehydelelectricity,high-risedamsareconstructedontheriverto

obstructtheflowofwaterandtherebycollectwaterinlargerreservoirs.Thewater

LAKSHYA STUDY POINT

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levelrisesandinthisprocess,thekineticenergyofflowingwatergetstransformed

intopotentialenergy.Thewaterfromthehighlevelinthedamiscarriedthrough

pipes,totheturbine,atthebottomofthedam.Sincethewaterinthereservoirwould

berefilledeachtimeitrains(hydropowerisarenewablesourceofenergy)wewould

nothavetoworryabouthydro-electricitysourcesgettingusedupthewayfossilfuels

wouldgetfinishedoneday.

i. Whattypeofsourceofenergyismentionedintheabovepicture?

ii. Howdoeselectricitycanbegeneratedwithahydropowerplant?

iii. Whichformofenergyofflowingofwatergetstransformed?

iv. Whydamisconstructedacrosstheriverorastream?

4. Environmentaltriggerssuchaslight,orgravitywillchangethedirectionsthatplant

partsgrowin.Thesedirectional,ortropic,movementscanbeeithertowardsthe

stimulus,orawayfromit.So,intwodifferentkindsofphototropicmovement,shoots

respondbybendingtowardslightwhilerootsrespondbybendingawayfromit.How

doesthishelptheplant?Plantsshowtropisminresponsetootherstimuliaswell.The

rootsofaplantalwaysgrowdownwardswhiletheshootsusuallygrowupwardsand

awayfromtheearth.Thisupwardanddownwardgrowthofshootsandroots,

respectively,inresponsetothepullofearthorgravityis,obviously,geotropism.If

‘hydro’meanswaterand‘chemo’referstochemicals,whatwould‘hydrotropism’and

‘chemotropism’mean?Canwethinkofexamplesofthesekindsofdirectionalgrowth



movements?Oneexampleofchemotropismisthegrowthofpollentubestowards

ovules,aboutwhichwewilllearnmorewhenweexaminethereproductiveprocesses

oflivingorganisms.

Answerthefollowingquestions:

a. Wheredoesnegativephototropismoccursinplants?

b. Phototropisminshootsisattributedduetowhichplanthormone?

c. Tendrilsexhibit/twiningoftendrilsshowwhichtypeoftropicmovement?

d. Ifthestemgrowstowardssunlightandrootgrowsjustoppositetoit,thenwhat

typeofmovementofstemisit?

5. Whenapersonissufferingfrombothmyopiaandhypermetropia,whattype

correctivelensarerequired-

a. Convex

b. Noneofthese

c. Bifocal

d. Concave

OR

Atwhatratetheeventshouldbeprojectedtohavetheclearimage?

a. 24framespersecond

b. 20framespersecond



c. 22framespersecond

d. 25framespersecond

6. StatementA:Groundwaterisprotectedfromcontaminationbyhumanandanimal

waste,StatementB:regionsofwaterscarcityarecloselyrelatedtotheregionsofacute

poverty

a. StatementAistrue,Bisfalse

b. BoththestatementAandBaretrue

c. StatementBistrue,Aisfalse

d. NeitherstatementAnorstatementBistrue

7. Potentialdifferencebetweenalivewireandaneutralwireis

a. 150volt

b. 220volt.

c. 210volt

d. 200volt

8. Abluelitmuspaperwasfirstdippedindil.HClandthenindil.NaOHsolution.Itwas

observedthatthecolourofthelitmuspaper

a. changedfirsttoredandthentoblue

b. changedtored

c. remainedblueinboththesolutions

d. changedfirsttoredandthentoblue

OR

Saltofastrongbaseandaweakacid

a. arebasicwithpH>7



b. areneutralwithpH=7

c. areacidicwithpH>8

d. areacidicwithpH<7

9. Inwhichofthefollowingfoodchains,doesmangetmoreenergy?(i)Plant Man(ii)

Plant Goat Man

a. (i)Plant Man

b. (ii)Plant Goat Man

c. Noneoftheabove

d. Equalenergyin(i)&(ii)

10. Organismsofahighertrophiclevelwhichfeedonseveraltypesoforganisms

belongingtoalowertrophiclevelconstitutethe

a. Ecosystem

b. Ecologicalpyramid

c. Foodweb

d. Foodchain

11. Whichoneofthefollowingisthemostreactive?

a. Bromine

b. Iodine

c. Chlorine

d. Fluorine

12. Matchthefollowingwiththecorrectresponse:

(1)Metal (A)Acidicoxides

(2)Non-metal (B)Neutral



(3)Amphoteric (C)Bothacidicandbasicoxides

(4)Salts (D)Basicoxides

a. 1-D,2-A,3-C,4-B

b. 1-C,2-B,3-D,4-A

c. 1-A,2-C,3-B,4-D

d. 1-B,2-D,3-A,4-C

13. Assertion:PropenereactswithHBrtogiveisopropylbromide.

Reason:AdditionofBr2toalkenetakesplaceatthefasterrateinthepresenceof

ionizingsubstance.

a. BothassertionandreasonareCORRECTbut,reasonisNOTTHECORRECT

explanationoftheassertion.

b. AssertionisINCORRECTbut,reasonisCORRECT.

c. BothassertionandreasonareCORRECTandreasonistheCORRECTexplanationof

theassertion.

d. AssertionisCORRECTbut,reasonisINCORRECT.

14. Assertion:Positivechargeinsidethecellalwaysgoesfrompositiveterminaltothe

negativeterminal.

Reason:Positivechargeinsidethecellmaygofromnegativeterminaltothepositive

terminal.

a. AssertionisINCORRECTbut,reasonisCORRECT.

b. AssertionisCORRECTbut,reasonisINCORRECT.

c. BothassertionandreasonareCORRECTbut,reasonisNOTTHECORRECT

explanationoftheassertion.

d. BothassertionandreasonareCORRECTandreasonistheCORRECTexplanationof

theassertion.

SectionB

15. Whatisefflorescence?Giveanexample?



16. AsubstanceXusedforcoatingironarticlesisaddedtoabluesolutionofareddish-

brownmetalY.Thecolorofthesolutionfadesaway.IdentifyXandYandthetypeof

thereactioninvolved.

OR

Identifythesubstancesthatareoxidizedandthesubstancesthatarereducedinthe

followingreactions.

(i)

(ii)

17. Whydogroup1elementsformunipositiveions?

18. Whyarewhitebloodcorpusclescalledsoldiersofthebody?

OR

Namethehormonessecretedbythefollowingendocrineglandsandspecifyone

functionofeach:

a. Thyroid

b. Pituitary

c. Pancreas

19. Whatismeantbypowerofaccommodationofeye?

20. Explainspeciation.

21. Whatisreflexaction?Giveexamplesofreflexaction.

22. Namesomesourceofdirectcurrent.

23. AChildhasdrawntheelectriccircuittostudyOhm'slawasshowninFigure.His

teachertoldthatthecircuitdiagramneedscorrection.Studythecircuitdiagramand

redrawitaftermakingallcorrections.



24. Inthefiguregivenbelow,anarrowbeamofwhitelightisshowntopassthrougha

triangularglassprism.Afterpassingthroughtheprism,itproducesaspectrumXYon

thescreen.

i. Namethephenomenon.

ii. StatethecoloursseenatXandY.

iii. Whydodifferentcoloursofwhitelightbendatdifferentanglesthroughaprism?

OR

i. Whatshouldbethepositionoftheobjectwhenaconcavemirroristobeused

a. asashavingmirrorand

b. intorchesproducingparallelbeamoflight?

ii. Amanstandinginfrontofamirror,findshisimagehavingaverysmallheadand

legsofnormalsize.Whattypeofmirrorsareusedindesigningsuchamirror?

SectionC

25. i. Howdoyouclassifyelementsintometalsandnon-metalsonthebasisoftheir

electronicconfiguration?Choosemetalandnon-metaloutofthefollowing:

ii. Whattypeofbondwillbeformedif

a. 'A'combineswith'B'?

b. 'A'combineswith'E'?

c. 'C'combineswith'E'?

d. 'D'combineswith'E'?



26. a. Namethegasevolvedduringfermentationprocess.

b. Whatroleisplayedbyyeastintheconversionofcanesugar(C12H22O11)to

ethanol?

c. Howcanthefollowingbeobtainedfrompureethanol?Expresschemicalreactions

bythechemicalequations.

i. Sodiumethoxide

ii. Ethylethanoate

iii. Ethanal

27. Describethestructureandfunctioningofnephrons.

28. Differentiatebetweenthefollowing:

i. Pollentubeandstyle

ii. FissioninAmoebaandplasmodium

iii. Fragmentationandregeneration

iv. BudofHydraandBryophyllum

v. Vegetativepropagationandsporeformation

OR

Withthehelpofalabelleddiagramdescribedoublefertilizationinplants.

29. Aletter'A'consistsofauniformwireofresistance1ohmcm-1.Thesideoftheletter

areeach20cmlongandthecross-pieceinthemiddleis10cmlongwhileapexangle

is60o.Findtheresistanceoftheletterbetweenthetwoendsofthelegs.

30. Astudentwantstoprojecttheimageofacandleflameonthewallsofschool

laboratorybyusingalens.

i. Whichtypeoflensshouldheuseandwhy?



ii. AtwhatdistanceintermsoffocallengthFofthelensshouldheplacethecandle

flame,soastoget

a. amagnifiedand

b. adiminishedimagerespectively,onthewall?

iii. Drawraydiagramstoshowtheformationoftheimageineachcase.

OR

Anobject2cmhighisplacedatadistanceof16cmfromaconcavemirrorwhich

producesarealimage3cmhigh.

(i)Whatisthefocallengthofthemirror?

(ii)Findthepositionoftheimage.



CBSEClass10Science

SamplePaper01(2019-20)

Answer

SectionA

1.

Ferrous

sulphate+

Sodium

hydroxide→ Ferroushydroxide + Sodiumsulphate

FeSO4 + 2NaOH → Fe(OH)2 + Na2SO4

2. Elementswithatomicnumbers12and38havethesimilarchemicalandphysical

propertiesofcalcium.

3. i. Itisarenewablesourceofenergy.

ii. Hydropowerplantscapturetheenergyoffallingwatertogenerateelectricity.A

turbineconvertsthekineticenergyoffallingwaterintomechanicalenergy.Then

ageneratorconvertsthemechanicalenergyfromtheturbineintoelectrical

energy.

iii. Thekineticenergyofflowingwatergetstransformedintopotentialenergy.

iv. ADamisbuilttocontrolwaterthroughplacementofablockageofearth,rock

acrossastreamorriver.Theyusuallystorewaterinthereservoir,whichisthen

usedforavarietyofapplicationssuchasirrigationandmunicipalwatersupplies.

4. a. Root

b. Auxin

c. Thigmotropism

d. Positivephototropicmovement.

5. (c)Bifocal,Explanation:Bifocallensesconsistofbothconcaveandconvexlens,

upperpositionconsistoftheconcavelensandlowerportionconsistofconvexlens.

OR

(a)24framespersecond,Explanation:Framerate(expressedinframespersecond

orfps)isthefrequency(rate)atwhichconsecutiveimagescalledframesaredisplayed



inananimateddisplay.Thehumaneyeiscapableofdifferentiatingbetween10and12stillimagespersecondbeforeitstartsjustseeingitasmotion.Thatis,atanFPSof12orless,ourbraincantellthatitsjustabunchofstillimagesinrapidsuccession,notaseamlessanimation.Oncetheframerategetsuptoaround18to26FPS,themotioneffectactuallytakeseffectandourbrainisfooledintothinkingthattheseindividualimagesareactuallyamovingscene.Thecurrentindustrystandardis24FPS.

6. (b)BoththestatementAandBaretrue,Explanation:Asthegroundwaterisstored

deepinsideitisusuallyprotectedbycontaminationofhumanandanimalwastes.

Availabilityofwaterleadstodevelopmentofaregionduetothegrowthofvarious

industries,agricultureanditsrelatedindustries.Theseprovideemploymenttothe

localpeopleandthushelptoreducepoverty.Hencewaterscarcityareclosely

correlatedtotheregionsofacutepoverty.

7. (b)220volt.,Explanation:Inourcountrythepotentialdifferencebetweenthelive

andneutralwireis220Vandthefrequencyis50Hz.

8. (d)changedfirsttoredandthentoblue

Explanation:Bluepaperturninredindicatethesampleisacidic.Bluepaperthat

doesnotchangecolorindicatesthesampleisabase.HClisacidicandNaOHisbase,

So,dil.HClturnsbluelitmusredwhichbecomesblueagaininNaOH.

OR

(a)arebasicwithpH>7Explanation:

Inaqueousmedium,strongbaseiscompletelydissociated,butweakacidisnot.

Hencesaltformedisbasic.So,itspH>7.

9. (a)(i)Plant Man,Explanation:Accordingtoanextensivestudy,10%canbetaken

astheaveragevaluefortheamountoforganicmatterthatispresentateachstep

andreachesthenextlevelofconsumers.Therefore,mangetsmoreenergyinthefirst

foodchain.Inthefirstcase,mangetsaround10%oftheenergyproducedbythe

plant.Inthesecondcase,mangetsaround1%oftheenergyproducedbytheplant.

10. NotAvailable

11. (d)Fluorine,Explanation:Ofallthehalogensgiven,Fluorineisthemostreactiveas



thereactivityofnon-metalsdecreasesongoingdownthegroup.

12. (a)1-D,2-A,3-C,4-B,Explanation:Mostmetalsformbasicoxides.Non-metalsform

acidicoxides.Amphotericsubstanceslikezincandaluminiumformbasicoxidesas

wellasacidicoxides.Mostsaltsareneutralinnature.

13. (a)BothassertionandreasonareCORRECTbut,reasonisNOTTHECORRECT

explanationoftheassertion.Explanation:BothassertionandreasonareCORRECT

but,reasonisNOTTHECORRECTexplanationoftheassertion.

14. (a)AssertionisINCORRECTbut,reasonisCORRECT.Explanation:Assertionis

INCORRECTbut,reasonisCORRECT.

SectionB

15. Itistheprocessofthelossofmoleculesofwaterofcrystallizationfromasubstance

whenexposedtoair.Forexample:

16. ThereddishbrownmetalYisCopper(Cu)andthesubstanceusedforcoatingiron

articlesisZinc(Zn)i.e.X.

Zn(s)+CuSO4(aq) ZnSO4(aq)+Cu(s)

Thisisanexampleofasingledisplacementreactionwhereamorereactivemetal

displacesalessreactivemetalfromitssaltsolution.

OR

(i)

Inthisreaction,Naisoxidizedbecauseitcombineswith toform . is

reducedbecauseitisconvertedinto .

(ii)

Inthisreaction, isreducedbecauseitlosesoxygen. isoxidizedbecauseit

combineswithoxygenof toformwater.

17. Group1elementscontain1electronintheiroutermostshells.Theseelementslose

thiselectroneasilytoattainthe8electronsconfigurationintheiroutermostshell,to

attainstableconfiguration.Hence,theyformunipositiveion.



18. Whitebloodcorpusclesengulf(phagocytose)theforeignmatter(bacteria,dustand

otherforeignmaterial)enteringthebodyandactasalineofdefense.Hence,WBC's

calledsoldiers.Theyproduceantibodiesagainstantigens,andantitoxinsagainst

toxins.

OR

a. ThyroidexcretesThyroxinehormone.Itregulatescarbohydrate,proteinandfat

metabolisminthebodysoastoprovidethebestbalanceforgrowth.

b. PituitaryexcretesGrowthhormone.Itregulatesgrowthanddevelopmentofthe

body.

c. PancreasexcretesInsulinhormone.Itregulatesbloodsugarlevel.

19. Theabilityoftheeyelens,toadjustitsfocallength,soastoclearlyfocustherays

comingfromdistantaswellasnearobjectsontheretina,iscalledthepowerof

accommodationoftheeye.Thisisaccomplishedbytheciliary

muscle,whichcontrolstheeye

lens,allowingittoflattenorthickenasisneededfordistantornearvision.

20. Whenenvironmentalconditionschangeorasectionofthepopulationmigratestoa

newareawithdifferentenvironmentalconditions,newspeciesmayarise.Originof

newspeciesfromtheexistingoneiscalledspeciation.Inthechangedenvironment,

populationmaybecomeadaptedordieout.Apopulationbecomesadaptedifits

individualshavesomenewtrait(geneticvariation)whichsuitsthechanged

environmentandisselectedbynatureonthisbasis.Thenewtraitspreadsby

differentialreproductionandintimebecomesastandardfeatureofasectionofthe

population.Thisistheunitofevolutionarychange.Accumulationofmanysuchunit

changesinasectionofthepopulationmaysufficientlyaltertheindividualsin

structureorfunctiontobecomeanewspecies.Thelatterarenolongerableto

interbreedwithparentalpopulation.

21. Spontaneous,mechanicalinvoluntaryresponsebyvoluntaryorganstoastimulusis

calledreflexaction.

Examplesofreflexaction:

i. Ifthehandissuddenlyprickedwithneedle,itiswithdrawnimmediately.



ii. Wateringofmouthonlookingdeliciousdishes.

iii. Closingofeyesinresponsetosuddenflashlight.

22. Sourceofpuredirectcurrentisacell.Allotherproducefluctuatingdirectcurrent.

23. Correctdiagramisasfollows:

24. i. Thephenomenoniscalleddispersion.

ii. X—VioletY—Red

iii. Differentcoloursofwhitelightbendthroughdifferentangleswithrespecttothe

incidentbeamoflightduetodifferenceinspeedoflightofdifferentwavelengths.

OR

i. a. Objectshouldbebetweenpoleandfocus.

b. Atthefocus.

ii. a. Smallhead-convexmirror.

b. Legsofnormalsize-planemirror.

SectionC

25. i. Elementswhichcontain1to3electronsintheiroutermostshellaremetals.

Elementscontaining4to7electronsintheirvalenceshellarenon-metals.

Electronicconfigurations:



HenceAandCaremetalswhereas,B,DandEarenon-metals.

ii. Typeofbonds

a. 'A'ismetaland'B'isnon-metal,sothebondformedwillbeionic.

A=2,8,1B=2,7

b. 'A'ismetaland'Eisnon-metal,sothebondformedisionic.

A=2,8,1B=2,7

c. 'C'ismetaland'E'isnon-metal,sothebondformedisionic.

C=2,8,2E=2,8,7

d. 'D'isanon-metaland'E'isalsoanon-metal,sothebondformedwillbe

covalent.

26. a. Thegasthatisevolvedisevolvedduringthefermentationprocessiscarbon

dioxide(CO2).Itisaccompaniedbybriskeffervescence.

b. Yeastisthesourceofenzymes-invertaseandzymase.Theseenzymesareneeded

forfermentationofcanesugar(C12H22O11)toethanol.



Invertasehelpsinbreakingsucrose(anaturallyoccurringcarbohydratepresent

incanesugar)intoitscomponents-glucoseandfructose.

Zymaseconvertsglucoseintoalcoholandcarbondioxide.

c. Therequiredchemicalreactionsforpureethanolareasfollows:-

i. Sodiumethoxide( )canbeobtainedfrompureethanolwhenitis

madetoreactwithsodium.Sodiumdisplaceshydrogenfromethanol.

ii. Ethylethanoatecanbeobtainedfrompureethanolbywarmingethanolwith

ethanoicacidinthepresenceofconc.sulphuricacid.Thisisesterification

reaction.

C2H5OH+CH3COOH +H2O

iii. Ethanalcanbeobtainedbyperformingthepartialoxidationofpureethanolin

theabsenceofwater.Achromiumbasedreagentsuchaschromiumtrioxide

canbeused.

C2H5OH+ O2 CH3CHO+H2O

27. StructureofNephron:Nephronisthestructuralandfunctionalunitofkidney.



i. Itconsistsofalongcoiledtubuledifferentiatedintoproximaltubule,loopofHenle

anddistaltubule.Thelatteropensintothecollectingtubule.

ii. Attheproximalendofthenephronliesadouble-walledcup-shapedstructure

calledBowman’scapsule.

iii. TheBowman’scapsulecontainsabundleofbloodcapillarieswhichiscalled

glomerulus.

iv. Intheglomerulus,thebloodthatcomesinthroughafferentarterioleisdrained

outthroughefferentarteriole.

FunctionsofNephron:

i. Filtration:FiltrationofbloodtakesplaceinBowman’scapsulefromthecapillaries

ofglomerulus.Thistakesplaceunderhighpressure.Thefiltratepassesintothe

tubularpartofthenephron.Thisfiltratecontainsglucose,aminoacids,urea,uric

acid,saltsandmajoramountofwater.

ii. SelectiveReabsorption:Asthefiltrateflowsalongthetubule,usefulsubstances

suchasglucose,aminoacids,saltsandwaterareselectivelyreabsorbedintothe

bloodbycapillariessurroundingthenephrontubule.Theamountofwater

reabsorbeddependsontheneedofthebodyandalsoontheamountofwastesto

beexcreted.

iii. Tubularsecretion:Certainsubstanceswhichareharmfulandnotneededbythe

bodylikeammonia,potassium,creatinineandhydrogenionsaresecretedfrom

thecapillarybloodintothelumenofdistaltubule.Thisiscalledtubularsecretion.

28. i. Differencesbetweenpollentubeandstyleare:

PollenTube Style

Itispartofmalegamete.Whenpollen

grainstickstoflowerstigmaatube

growingoutofpollengrainbetterknown

aspollentube.

Themiddleelongatedpartofthe

carpel,i.e.femalepartofaflower.

Whichallowspathforpollentube

togrow.

Ittransportsmalegametesfrompollen

grainstoovules.

Theattachmentofstigmatothe

ovary.

ii. Differencebetweenfissioninamoebaandplasmodiumis

FissioninAmoeba FissioninPlasmodium



Thefissioninamoebaisbinary

fission.

Thedivisionofparentalbodyinto

twoidenticaldaughtercellsatatime.

Thus,thesizeiscomparativeto

parentcell.

Thefissioninplasmodiumismultiple

fission.

Theparentalbodydividesintonumerous

daughtercellssimultaneously.Herethe

daughtercellsarenumerousandvery

small.

iii. Differencebetweenfragmentationandregenerationis:

Fragmentation Regeneration

Themethodinwhich

multicellularorganismbreaks

upintotwoormoresmaller

fragments.

Thegrowthofawholeneworganismfrom

anyofitsbody,withthehelpofspecial

cells.i.e.singlesegmentformingnew

individual.

iv. DifferencebetweenbudofHydraandBryophyllumis:

BudofHydra BudofBryophyllum

Itisseenduringbuddingasan

outgrowthonthebodyofHydra

whichgetsfullygrownandthen

detachesfromthebodyand

becomesanewindividual.

Thisispresentontheleavesof

Bryophyllumdevelopintoanewplant

whenitcomesincontactwithsoilandother

favourableconditions.Thebudhereare

numerousinsingleleafatatime

v. Differencebetweenvegetativepropagationandsporeformationis:

Vegetativepropagation SporeFormation

Newplantsareobtainedfrom

differentpartsofparentbody

likeleaves,stems,etc.Itisa

formofasexualreproduction

thatcanbenaturalor

inducedartificially.

Sporeformationisalsoanasexualreproduction

procedurewhichoccurinnon-floweringplants.

Parentplantproducenumerousspores.Spores

whenfallonland,havetheabilitytogerminate

andproducenewfungalcoloniesunder

favourableconditions.

OR

Doublefertilization:InAngiospermsboththemalegametesarefunctional.Double

fertilizationisaprocessinwhicheggnucleusandsecondarynucleusarefertilizedat



onetimebytwomalegameticnuclei.Thefusionofonemalegametenucleus(IN)with

eggoroosphere(IN)iscalledsyngamyandresultsintheformationofoospore(2N).

Thefusionofsecondmakenucleus(IN)withsecondarynucleus(2N)iscalledtriple

fusionwhichresultsinformationofprimaryendospermnucleus(3N).

Significance.

i. Doublefertilizationprovidesstimulustoendospermmothercellfortheformation

ofnutritivetissuenamedendosperm.

ii. Itensurescontinuedsupplyofnourishmenttotheembryothatdevelopsfrom

zygote.

29. Thearrangementofresistanceisshowninfig.(a)anditsequivalentcircuitisshown

infig(b).

Fig.(a)

Fig.(b)

Sincethewirehasaresistanceof1Ωcm-1,theresistanceofcross-piecedeis10Ω.

Sinceapexangleis600andthecross-pieceis10cm.long,theendsdandeofthe

cross-piecemustbethemid-pointofthelegsabandacsothatadebecomesan

equilateraltriangles.

Asitisclearfromthefig.daandaeareinseries.Therefore,resistanceofthe



combinationofdaandae=10+10=20Ω.This20Ωresistanceisparalleltode.

∴Effectiveresistanceroftheportiondaedisgivenby

Nowbdandecareinserieswiththeresistanceofportiondaed.

∴Resistancebetweenbandc=10+ +10= =26.67Ω

30. i. Heshoulduseaconvexlensasrealimagesareformedbyaconvexlens,when

objectsareplacedbetweenthefocusandinfinity.

ii.

a. Formagnifiedimagecandleshouldbeplacedbetweenfocus(F)andcentreof

curvature(2F)oflens.

b. Togetdiminishedimagecandleshouldbeplacedbeyondcentreofcurvature

(2F)oflens.

iii.

a. Formagnifiedimage,(objectbetweenFand2F).

b. Fordiminishedimage,(objectbeyond2F).

OR

Sincetheimageformedisreal,henceaninvertedimageisformed.

sizeofimage,h2=-3cm,sizeofobjecth1=+2cm.

Magnification .Also

Herev=-16cm(uisalwaysnegative)

Substitutingin(i),wehavev=-(-1.5)(-16)=-24cm.orv=-24cm.

Imageisformed24cmtotheleftofthemirror(Negativesign–Imageistowardsleft

ofmirror)

Tocalculatefocallength.Hereu==16cm,v=-24cm,f=?

Using

Negativefocallengthindicatesthatthemirrorisconcave.


Download - LAKSHYA STUDY POINT - CBSEGuess 1.pdfLAKSHYA STUDY POINT. Material downloaded from myCBSEguide.com. 2 / 21 level rises and in this process, the kinetic energy of flowing water gets

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