[1]

Section – A

1. Name the muscle that regulates the movement of food from stomach to small intestine. [1]2. Who is known as the 'Water man of India' and why? [1]

Section – B

3. What is Thermite reaction? Mention its application. [1+1]4. What are fossils and explain how fossil records provide us an evidence in favour of evolution?

[2]5. What are the factors on which refractive index of a medium depends? [2]

OR Drawaraydiagramtoshowthepathof reflectedraywhen incident ray fallsonaconcave

mirror, parallel to its principal axis. [2]

Section – C

6. (a) Why do we store silver chloride in dark colored bottles? [1½] (b) Grapes hanging on a plant do not ferment but after being plucked from the plant can be

fermented. Under what conditions do these grapes ferment? Is it a chemical change or a physical change? [1+½]

(2018-19)Date: ____________Duration : 3 Hrs.Max. Marks : 80

ClassXGeneral Science

Instructions:(i) Thequestionpapercomprisesoffivesections–A,B,C,DandE.Youaretoattemptallthesections.(ii) Allquestionsarecompulsory.(iii) InternalchoiceisgiveninsectionsB,C,DandE.(iv) Questionnumbers1and2inSection-Aareonemarkquestions.Theyaretobeansweredinonewordorinone

sentence.(v) Questionnumbers3to5inSection-Baretwomarksquestions.Thesearetobeansweredinabout30words

each.(vi) Questionnumbers6to15inSection-Carethreemarksquestions.Thesearetobeansweredinabout50words

each.(vii) Questionnumbers16to21inSection-Dare5marksquestions.Thesearetobeansweredinabout70words

each.(viii) Questionnumbers22to27inSection-Earebasedonpracticalskills.Eachquestionisatwomarksquestion.

Thesearetobeansweredinbrief.

Sample Paper

[2]

chemical formulae of A, B and C. [3]

OR State in brief the preparation of washing soda from baking powder. Write the balanced chemical

equation of the reaction involved in the process. Write any two uses of washing soda. [1+1+1]8. A quiz contest was being held in the school for chemistry students. The quiz-master said: An

elementhastheelectronicconfiguration2,8,7. (a) What is the atomic number of this element? (b) Which of the elements N, F, P and Ar shows similarity with this elements? Why? (c) A compound of this element causes hardness of water. What is that? Rohit replied to all these questions correctly. Can you reproduce his answers? [3]9. (a) ‘‘It is a matter of chance whether a couple will have a male or a female child.’’ Justify this

statementbydrawingaflowchart. [2+1] (b) ForwhichcharacteristicsdidweartificiallymakeCabbageandCauliflowerfromthewild

cabbage?10. (a) Tracethesequenceofeventsthroughareflexarcwhichoccurswhenabrightlightis

focussed on your eye. (b) Name the gland which is responsible for the following: (i) A person is suffering from Diabetes (ii) Takes care of the 3F situation of the body. [2+1]11. TheImageofacandleflameplacedatadistanceof45cmfromasphericallensisformedon

a screen placed at a distance of 90 cm from the lens. Identify the type of lens and calculate its focallength.Iftheheightoftheflameis2cm,findtheheightofitsimage. [3]

OR Draw a ray diagram in each of the following cases to show the position and nature of the image

formed when the object is placed: [1.5+1.5] (a) between optical centre (O) and principal focus (F) of a convex lens. (b) at2Fofaconvexlens.12. (a) Howwillyouconnect3resistances,eachof2ohms,sothateffectiveresistanceisthatof

3 ohms? Draw a circuit diagram depicting your connection. (b) State Joule's Law of heating. [2+1]13. A100wattelectricbulbislightedfor2hoursdailyandfour40wattbulbsarelightedfor4

hours every day. Calculate the electrical energy consumed in kWh in 30 days. [3]14. (a) Mention the main constituents of biogas along with its percentage. [1] (b) What are the limitations of harnessing wind energy? [2]15. (a) What is the role of bacteria in an ecosystem? [1+1+1] (b) Whatisbiologicalmagnification? (c) Whyistheflowofenergyinanecosystemalwaysunidirectional?

)

7. Identify the compound X on the basis of the reactions given below. Also, write the name and

[3]

Section – D16. (a) A, B and C are three elements which undergo chemical reactions in the following way:

[1½+1½] (i) A2O3+2B→ B2O3+2A (ii) 3CSO4+2B→ B2(SO4)3 + 3C (iii) 3CO+2A→ A2O3 + 3C Answer the following: (I) Which element is most reactive? Why? (II) Which element is least reactive? Why? (b) Show the formation of Na2O by the transfer of electrons. [2]17. (a) WhatisHomologousseries?Namethe2ndand3rdhomologueinthehomologousseries

of Alcohols. [1+1] (b) Give reasons for the following:- [3] (i) Unsaturated hydrocarbons show addition reactions. (ii) Conversion of ethanol to ethanoic acid is an oxidation reaction.18. (a) Name the blood vessel that (i) brings nitrogenous wastes to the kidneys for removal. (ii) is taking the blood away from the kidneys after the removal of nitrogenous wastes. (b) When do the desert plants take-up carbon dioxide and how do they perform photosynthesis? (c) Draw a neat labelled diagram of the digestive system and label the following – (A) Organ in which digestion gets completed (B) Organ that secrete Bile juice (C) J shaped organ (D) Organ in which undigested food is stored [1+1+3]19. (a) DifferentiatebetweenMustardandPapayaflower. [1+1+3] (b) Mentionanytwochangesthattakeplaceinaflowerafterfertilization. (c) Label all the parts given in the diagram below and give the function of part B and D.

OR (a) How do variations arise in an individual organism and how is it advantageous to them? (b) Name the following: (i) Part in which the testis descend. (ii) Part in which sperms are stored temporarily. (iii) Structure which provide nutrition to the developing embryo. (iv) Process by which the unfertilized egg and the uterus lining is shed out of the body. (c) Which fertilization is advantageous to an organism and why? [2+2+1]

[4]

[3] (i) What kind of defect in vision is she suffering from? (ii) What is the focal length of the corrective lens? (iii) What is the nature of the corrective lens?21. (a) What is electromagnetic induction? Also state the rule which is closely related to this. (b) Withthehelpofalabelleddiagram,explainthedistributionofmagneticfieldduetoa

current through a circular loop. (c) Anelectronmovingintheupwarddirectiondeflectstowardleftinamagneticfield.Find

thedirectionofmagneticfield. [2+2+1]OR

(a) Drawthepatternofmagneticfieldlinesthroughandaroundacurrentcarryingsolenoid. (b) ABisacurrentcarryingconductorintheplaneofthepaperasshowninthefigure. (i) Whatarethedirectionofmagneticfieldofmagneticfieldsproducedbyitatpoints

P and Q? (ii) Given r1 > r2,wherewillthestrengthofthemagneticfieldbelarger?

(c) Explain the underlining principle of an electric generator. What is the function of the brushes? [2+2+1]

Section – E

22. A student dropped few pieces of marble in dilute hydrochloric acid contained in a test tube. The evolved gas was then passed through lime water. What change would be observed in lime water? Write balanced chemical equation for both the change observed? [2]

OR Parnita took three metals zinc, copper and aluminium. A named it as P, Q and R. She carried

out displacement reaction with their salt solutions and found that P is less reactive than R but more reactive than Q. Arrange the metals as per P, Q and R. [2]

23. A student addsa spoon full of powdered sodiumhydrogen carbonate to aflask containingethanoic acid. List two main observations that he/she must note in his/her notebook about the reaction that takes place. Also, write chemical equation for the reaction [2]

24. Explain the steps of preparing a mount of a peel of a leaf to study the structure of stomata. [2]OR

With reference to the experiment that carbon dioxide is given out during respiration answer the following questions:

(a) Why does the water rises in the delivery tube? (b) Whatwouldhappenifathermometeriskeptintheconicalflaskwiththegerminating

seeds?25. DrawaneatlabelleddiagramofBinaryfissioninAmoeba. [2]26. (a) While experimentally verifying Ohm's law, a student observed that the pointer of the

voltmetercoincideswiththe15thdivision.Whenthevoltmeterhastheleastcountof0.05V,findtheobservedreadingofvoltmeter.

(b) What is likely to happen if we pass the current for a longer time in the circuit in Ohm's law experiment? [1+1]

20. (a) Why do stars twinkle while planets do not? [2] (b) Apersonneedsalensofpower-4.5Dforcorrectionofhervision.

[5]

27. Write two precautions to be taken while tracing the path of a ray of light passing through a rectangular glass slab for different angles of incidence. [2]

OR Refractive indices of media A, B, C and D are given below:

Medium Refractive IndexABCD

1.331.441.521.65

In which of these four is the speed of light maximum? Support your answer with reason. Find the refractive index of medium D with respect to medium A.

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1. Sphincter muscle that regulates the movement of food from stomach to small intestine

2. Dr Rajender Singh as he has built Johads and other structures to collect water in Rajasthan as he has helped in conservation and protection of water resources.

3. Thermite process :

When highly reactive metals such as Sodium, Calcium, Aluminium etc., are used as reducing agents they displace metals of lower reactivity from the compound.

These are exothermic reactions.

The amount of heat evolved is so large that the metals produced in molten state.

The reaction of iron oxide with aluminium is used to join railing of railway tracks or cracked machine parts. This reaction is known as the thermite reaction. [1+1]

Fe2O3(s)+2Al(s)→2Fe(l) + Al2O3(s) + Heat

3. Fossils are the remains or impressions of dead animals and plants. They are direct evidences of organic evolution and help in determining evolutionary relationships between different species when we compare the living related organisms with the fossils obtained.

5. The refractive index of a medium depends on the wavelength of the light. If the wavelength of light is less the refractive index will be high. Secondly it depends on the density of the substance.The intermolecular force between the molecules ofthesubstancewillaffecttherefractiveindex.Theindexisalsoinfluencedbythepermeabilityofthematerial. [2]

OR

[2]

6. (a) For preventing silver chloride from the sunlight because in presence of sunlight it reacts with sunlight and decompose into silver and chlorine. This reaction is known as photolytic decomposition reaction. [0.5+1]

2AgCl (s) Sunlight → 2Ag (s) + Cl2 (g)

(b) When grapes are attached to the plant, aerobic respiration takes place in the cells as the oxygen reaches there. But when plucked, no oxygen reaches the cell, therefore fermentation starts (anaerobic condition).

Fermentation is a chemical change in which sugar is converted to alcohol. [1+0.5]7. Reaction of bases with metals : (1) 2NaOH+Zn→ Na2ZnO2 + H2(g) SodiumZincate (2) NaOH+HCl→NaCl+H2O (3) NaOH + CH3COOH→CH3 COONa + H2O So A = Na2ZnO2

B = NaCl C = CH3 COONa [1+1+1]

OR (b) When baking soda is heated, sodium carbonate, water and CO2 are produced. Sodium carbonate obtained is dissolved in water and crystals of washing soda are obtained by crystallization.

[1]

2NaHCO3 D Na2CO3 + H2O + CO2 [1]

Washing soda is used in glass, soap and paper industries. [1]8. (a) Atomicnumber=17

(b) F - as it belongs to the same group as the element(Cl)

(2018-19)Date: ____________Duration : 1 Hr.Max. Marks : 30

ClassXGeneral Science

Hints/Solutions to Sample Paper

[7]

(d) CaCl2 or MgCl2 causes temporary hardness of water. [1+1+1]9. (a)

Thus which sperm carrying X and Y chromosome will fuse into the egg is not under the control of anyone but it is by chance.

(b) Cabbage – Very short distances between leaves Cauliflower–Forsterileflowers10. (a) Stimulus(Light) → Photoreceptor in eye → Sensory Neuron → Relay Neuron (CNS) → Motor Neuron → Eye

(Effector Organ) → Eye is shut (Effect) (b) (i) Pancreas (ii) Adrenal Gland

11. Given:

Objectdistanceu=−45cm

Image distance v = 90 cm

Theimageofacandleflameisformedonthescreen,soaconvexlensisused.

1 1 1f v u= −

1 1

90145f

= −−

1 1

90145f

= +

1 1 2

90390f

=+

+

1 1

30f=

\ f = 30 cm

Hence, it is a convex lens of focal length 30 cm.

Heightoftheflame(object)h1=2cm

Magnificationm = =hh

vu

2

1

h22 9045

18045

=×−

= −

h2=–4cm

Height of image h2=−4cm

Thus,theheightoftheimageis4cm.Theminussignindicatesthattheimageisformedbelowtheprincipalaxis.Thus, the image is real and inverted. [1+1+1]

OR

[1.5]

[8]

[1.5]

12. (a) It is given that effective resistance is 3 ohms

So3=2+1

two resistors must be connected in parallel to another resistor in series.

3W = 1W+2W

1 12

12

Ω Ω Ω= + .

So the connection would be like.

R1

2

2W

R2

R3

2

R‘X’ V

[1+1]

(b) JoulesLawstatesthatwhencurrentIflowthrougharesistorofelectricresistanceR,heatisproduced.Theheatproduced H depends directly on the square of the current, resistance and time t for which the current is allowed to pass.

H = I2 Rt, [1] SI unit Heat energy: joule

13. Energy consumed by electric bulb = P × T

Energyconsumedbyelectricbulbof100w=100w×30×2hrs

Energy consumed by electric bulb of 100 w = 3000 watt-Hr

Energy consumed by electric bulb of 100 w = 3 kilo watt-Hr

Energyconsumedbyfourbulbseachof40w=Numberofthebulbs×powerofeachbulb×Time

Energyconsumedbythefourbulbs=4×40w×4hrs×30

Energyconsumedbythefourbulbs=19200watt-Hr

Energyconsumedbythefourbulbs=19.2kilowatt-Hr

Totalenergyconsumed=Energyconsumedbyelectricbulbof100w+Energyconsumedbyfourbulbseachof40w

Totalenergyconsumed=3kilowatt-Hour+19.2kilowatt-Hour

Totalenergyconsumed=22.2kilowatt-Hour [3]14. (a) Methane CH4:50–75%

Carbon dioxide CO2:25–50%

Nitrogen N2:20–10%

Hydrogen H2:0–1%

HydrogensulfideH2S:0–3%

Oxygen O2:0–0.5% [1] (b) The limitations in harnessing wind energy are- 1. Thespeedofwindmustbehigh(min.15km/h) 2. Costofsettingupawindfarmishigh 3. Availability of land as per the requirements i.e. large lands in hilly regions with high speed wind. [1+1]15. (a) Thebacteriahelpincleaningtheecosystemandcyclicflowofnutrientsintheecosystem. (b) The increase in concentration of harmful chemical substances like pesticides in the body of living organisms at

eachtrophiclevelofafoodchainiscalledbiologicalmagnification. (c) Theflowofenergy isunidirectional.Theenergy that iscapturedby theautotrophsdoesnot revertback to

the solar input and the energy which passes to the herbivores does not come back to autotrophs. As it moves progressively through the various trophic levels it is no longer available to the previous level.

16. ???17. (a) Homologous series is a series of compounds with the same functional group and similar chemical properties in

[9]

which the members of the series differ by the number of repeating units they contain. [1+1] 2ndand3rdhomologueofalcohol:ethanolandpropanol (b) (i) Unsaturated hydrocarbon contains either double or triple bonds, which are reactive, so they break easily

and convert into single covalent bonds hence they easily undergo addition reactions. While saturated hydrocarbons have only single bonds which are strong hence they do not show addition reactions. [1.5+1.5]

(ii) CH3CH2OH + (Alkaline KMnO4)→CH3COOH Since, in this reaction one oxygen is added to ethanol, hence it is an oxidation reaction.18. (a) (i) Renal artery (ii) Renal vein (b) Desert plant take in carbon dioxide at the night and convert it into an intermediate product and convert it into

glucose in the day. (c)

[1+2]

19. (a)

Mustard flower Papaya flower

Itisabisexualflowerhavingboththesexorgansi.e.stamenandpistil,inthesameflower.

It is a unisexual flower having only one sex organeitherstamenorpistilinaflower.

(b) Anytwochangesthattakeplaceinaflowerafterfertilizationaretheovarydevelopsintoafruitandsepals,petals and stamen dry and fall off.

(c) A – Pollen grain B – Stigma C – Pollen tube D – Female gamete Function of B is that it acts as a landing surface for the pollen grains. Function of D is that it fuses with the male gamete and forms the zygote which later forms an embryo.

OR (a) The replication of DNA in the cell is done by certain biochemical reactions which synthesize more of genetic

material.Nobiochemicalreactioncanproduce100%sameresults.TheseslightvariationinthereplicationofDNA molecule will lead to slight variations in the offspring that gives them a better body design to adapt in the changing niche. For eg, if there is a population of bacteria living in temperate water and the temperature of water increases too much due to global warming, then most of these bacteria will not be able to tolerate excessive heat and hence die. But some bacteria which had variation to resist heat would survive and grow further.

(b) (i) Scrotum (ii) Epidydimus (iii) Placenta (iv) Menstruation (c) Internal fertilization is advantageous to the organism as the development of the embryo takes places in protected

environment thus ensuring better survival probability.20. (a) Stars twinkle because … they’re so far away from Earth that, even through large telescopes, they appear only as

pinpoints. And it’s easy for Earth’s atmosphere to disturb the pinpoint light of a star. As a star’s light pierces our atmosphere, each single stream of starlight is refracted – caused to change direction, slightly – by the various temperature and density layers in Earth’s atmosphere. [2]

(b) (i) She is suffering from myopia (ii) f=–22.22cm. (iii) It is a concave lens. [1+1+1]21. (a) Theprocessbywhichachangingmagneticfieldinaconductorinducesacurrentinanotherconductoriscalled

electromagnetic induction. Fleming’s Right-hand Rule: Stretchthethumb,forefingerandmiddlefingerofyourrighthandsuchthatthey

aremutuallyperpendicular.Iftheforefingerpointsinthedirectionofthemagneticfieldandthethumbinthedirectionofmotionofconductor,thenthemiddlefingerwillpointinthedirectionoftheinducedcurrent. [2]

[10]

(b) [2]

(c) Using Fleming's Left-hand Rule:Directionofmagneticfieldistowardssouth. [1]

OR

(a)

axis of magnet axis of magnet

magnetic lineof force

N S

[2]

(b) (i) ThedirectionsofmagneticfieldsproducedbyitatpointPisintotheplaneofpaperandoutofpaperatpoint Q. [2]

(ii) MagneticfieldatQisgreaterthanatP. (c) An electric generator converts mechanical energy into electrical energy. [1] Theprincipleofworkingofanelectricgeneratoristhatwhenaloopismovedinamagneticfield,anelectric

currentisinducedinthecoil.Itgenerateselectricitybyrotatingacoilinamagneticfield. Brushes of AC generator transfer current from the armature of the generator to the load in the circuit.

22. Marble is chemically calcium carbonate. When dilute HCl is added to calcium carbonate, it forms calcium chloride, water and carbon dioxide. The chemical equation for the reaction is as follows

CaCO3+2HCl→CaCl2 + H2O + CO2

Carbon dioxide gas turns lime water milky due to the formation of calcium carbonate. Following is the chemical equation showing the reaction between lime water and carbon dioxide.

Ca(OH)2 + CO2→CaCO3 + H2O [1+1]OR

?

23. Observations: 1. Briskeffervescence 2. Sodiumsaltformation

Reaction:

2CH3COOH + Na2CO3→2CH3COONa + CO2 + H2O.

24. Procedure: (a) Peel off the leaf from its under surface and put the peel in a watch glass containing water. (b) Add a few drops of safranin stain into the watch glass to stain the peel. (c) After staining put the peel on a clean slide and cut it in a rectangular or square shape. (d) Withthehelpofafilterpaper,removetheexcessofstainandwater. (e) Put a drop of glycerine on the slide over the peel, gently put the coverslip to avoid the entry of air bubbles and

observe under the microscope.

OR (a) The water rise in the delivery tube as Carbon Dioxide released by the germinating seeds during respiration is

absorbed by KOH and thus creating a vacuum and so water rises. (b) Ifathermometeriskeptintheconicalflaskwiththegerminatingseedsthetempinthethermometershowsa

rise as aerobic respiration releases some amount of energy too.

[11]

25.

26. (a) Least count of any device of measurement is the least reading it can take or measured by the device. LC = Value in n divisions/ n LC=0.05vandthepointer(n)isat15thdivision.

Therefore,theobservedreadingofthevoltmeter=0.05×15=0.75volts.

(b) As we know according to ohms law,

v = IR, where – v – potential difference

I – current

R – Resistance

I a 1R , it shows that current is inversely proportional to resistance that is as we increase the current the

resistance decrease. So, if we pass current for a long time the value of resistance decreases.27. 1. Thepinshouldbefixedonverticalpositionandallpinsshouldbeplacedinstraightline. 2. Angleofincidenceshouldbeliesbetween30°to60°.

OR If the speed of the light is more, refractive index will be less. 1. Speed of light will be maximum in A as it had less refractive index. 2. SpeedoflightisminimuminDasithasmorerefractiveindex.Refractiveindextheratioofthevelocityoflightina

vacuumtoitsvelocityinaspecifiedmedium.

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