CLASS X (2020-21) SCIENCE (CODE 086) SAMPLE PAPER-5

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Science X Sample Paper 5 Solvedwww.cbse.onlineCLASS X (2020-21)SCIENCE (CODE 086)SAMPLE PAPER-5Time : 3 HoursMaximum Marks : 80General Instructions :(i) The question paper comprises four sections A, B, C and D. There are 36 questions in the question paper. Allquestions are compulsory.(ii) Section–A – question no. 1 to 20 - all questions and parts thereof are of one mark each. These questions containmultiple choice questions (MCQs), very short answer questions and assertion - reason type questions. Answersto these should be given in one word or one sentence.(iii) Section–B – question no. 21 to 26 are short answer type questions, carrying 2 marks each. Answers to thesequestions should in the range of 30 to 50 words.(iv) Section–C – question no. 27 to 33 are short answer type questions, carrying 3 marks each. Answers to thesequestions should in the range of 50 to 80 words.(v) Section–D – question no. 34 to 36 are long answer type questions carrying 5 marks each. Answer to thesequestions should be in the range of 80 to 120 words.(vi) There is no overall choice. However, internal choices have been provided in some questions. A student has toattempt only one of the alternatives in such questions.(vii)Wherever necessary, neat and properly labelled diagrams should be drawn.Carbon exhibits this property because it forms strongcovalent bond.Section A1.An element M is in group 13 of the periodic table.What is the formula of its oxide?[1]Ans :3.Identify ‘x ’ in the following reaction:2AgCl (s)Ans : x sunlight4.x[1]2Ag (s) Cl 2 (g)Define the term dispersion of white tight.Ans :[1]The splitting up of white light into its componentcolours is called dispersion.5.orThe atomic numbers of three elements X,Y and Zare given below:ElementsAtomic NumbersX3Y9Z11Due to atmospheric refraction of sunlight, the apparentlength of the day is increased by 4 minutes.6.State giving reason which two elements will showsimilar chemical properties?Ans :ElementsAtomic NumbersElectronicConfigurationX32, 1Y92, 7Z112.8, 1X and Z will show similar chemical properties becauseboth of them have same number of valence electrons.Hence they belong to the same group (1).2.Which phenomenon is responsible for increasing theapparent length of the day by 4 minutes?[1]Ans :Which element exhibits the property of catenation tomaximum extent and why ?[1]Ans :A girl was playing with a thin beam of light fromher laser torch by directing it from different directionson a convex lens held vertically. She was surprised tosee that in a particular direction the beam of lightcontinues to move along the same direction afterpassing through the lens. State the reason for theobservation.[1]Ans :A ray of light passing through the optical centre ofthe convex lens will continue to move along the samedirection after refracting through the lens.orWhat is the nature and radius of curvature of themirror having focal length 15 cm ?Ans :Focal length of mirror is negative. Hence mirror isconcave in nature.Radius of curvature,Download 20 Solved Sample Papers pdf from www.cbse.onlineR 2f 2 ( 15) 30 cmPage 1

Science X Sample Paper 5 Solved7.In the device shown in figure, there is a rectangularcoil ABCD of insulted copper wire. The ends of thecoil are connected to the two halves of a split ring. [1]www.cbse.onlinein a plant.orWhat will happen to a plant if its xylem is removed?Ans :If xylem is removed from the plant, the water andmineral supply to the plant will stop and therefore,the plant will die.12. Which class of chemicals is linked to the decrease inthe amount of ozone in the upper atmosphere of theearth?[1]Ans :The chemical compound, chlorofluorocarbon ismainly responsible for decrease of ozone in the upperatmosphere.or8.What is the role of split ring in the given device?Ans :The first trophic level in a food chain is always a greenplant. Why?Ans :The split ring acts as a commutator in the givendevice, i.e., it reverses the direction of current throughthe circuit after every half-cycle.Only green plants can manufacture their own foodfrom sunlight: Hence, green plants always acquire thefirst trophic level in a food chain.Draw the magnetic field lines around a bar magnet. [1]Ans :13. Write the full form of DNA.Ans :[1]The full form of DNA is Deoxyribonucleic Acid.For question numbers 14, 15 and 16, two statementsare given-one labelled Assertion (A) and the otherlabelled Reason (R). Select the correct answer tothese questions from the codes (a), (b), (c) and (d) asgiven below :9.What happens to resistance of a conductor when itsarea of cross-section is increased?[1]Ans :We know that, R ? 1 i.e., on increasing the area ofAcross-section of a conductor, the resistance decreases.orHeating element of electrical heating devices is madeup of an alloy rather than a pure metal. Give tworeasons.Ans :Alloys are used for making elements of electricalheating devices because to the following reasons:(a) They have a higher resistivity as compared topure metals.(b) They do not burn in oxygen, i.e., they do notoxidise readily at high temperatures.10. Which enzyme present in saliva breaks down starch?[1]Ans :The saliva contains an enzyme called salivary amylasethat breaks down starch.11. Name the tissue which transports soluble products ofphotosynthesis in a plant.[1]Ans :Phloem transports soluble products of photosynthesis(a) Both A and R are true and R is correct explanationof the assertion.(b) Both A and R are true but R is not the correctexplanation of the assertion.(c) A is true but R is false.(d) A is false but R is true.14. Assertion : Covalent compounds have generally lowmelting and boiling points.[1]Reason : Covalent compounds are soluble in water.Ans : (c) A is true but R is false.15. Assertion : The enzymes released by micro-organismshelp in breaking down biodegradable wastes.Reason : Biodegradable wastes are generally inorganicwastes.[1]Ans : (a) A is true but R is false.16. Assertion : The embryo gets nutrition from themother’s blood with the help of a special tissue calledplacenta.Reason : Placenta transfers glucose and oxygen fromthe mother to the embryo.[1]Ans : (b) Both A and R are true but R is not thecorrect explanation of the assertion.orAssertion : Fertilisation cannot take place in flowers ifpollination does not occur.Reason : Fertilisation requires both male and femalegametes in a flower.Download 20 Solved Sample Papers pdf from www.cbse.onlinePage 2

Science X Sample Paper 5 Solvedwww.cbse.onlineAns : (a) Both A and R are true and R is correctexplanation of the assertion.17. Read the following and answer any four question 17.1to 17.5.1#4Sexually Transmitted Diseases (STDs) or SexuallyTransmitted Infections (STIs) are caused by bacteria,viruses or parasites that are transmitted throughunprotected sex and skin to skin genital contact.Bacterial infections include gonorrhoea, syphilis andLyphogranuloma Venerum (LGV) whereas viralinfections include warts, genital herpes and HIVAIDS. STIs are an important public health problemin India. ICMR estimates the occurrence of about 3035 million new infections in the country every year,almost half of them among adolescents and youngpeople.Birth control methods such as oral contraceptivesor IUDs do not prevent STD transmission, however,correct and consistent use of male condom is highlyeffective in reducing STD transmission.17.1Which of the following is not a sexually transmitteddisease?(a) gonorrhoea(b) hepatitis(c) syphilis(d) AIDSAns : (b) hepatitisIn a particular group, the elements (e.g., A, B, C ) withatomic masses 7, 23 and 39 respectively were arrangedin order of increasing atomic masses and the atomicmass of the middle element (B) was almost the meanor the average of the atomic masses of the first andthird elements i.e., A and C .18.1Which of the following scientist had proposedsuch a classification of elements?(a) Henry Mosely(b) Dmitri Mendeleev(c) John Newlands(d) Johann DobereinerAns : (d) Johann Dobereiner18.2What could be the elements A, B and C ?(a) Calcium, Strontium and Barium(b) Lithium, Sodium and Potassium(c) Lithium, Sodium and Calcium(d) Nitrogen, Calcium and IodineAns : (b) Lithium, Sodium and Potassium18.3The three imaginary elements X,Y and Zrepresent elements according to the given law. Ifthe atomic mass of element X is 14 and that of Yis 46, then the atomic mass of element Z will be:(a) 78(b) 32(c) 18(d) 60Ans : (a) 7817.2The sexually transmitted disease which is causedby bacteria is:(a) diarrhoea(b) AIDS(c) gonorrhoea(d) genital herpesAns : (c) gonorrhoea17.3Which of the following method of contraceptionprotects a person from acquiring a STD?(a) oral pills(b) copper-T(c) surgery(d) condomAns : (d) condom17.4Study the table below and select the row that hasthe incorrect Information.DiseaseCause(a)LGVBacteria(b)GenitaI s : (c) Syphilis-Virus17.5STIs are most common in which age group?(a) people 60 and older(b) people aged 40 to 50(c) adolescents and young people upto age 25.(d) none of theseAns : (c) adolescents and young people upto age 25.18.4What is the limitation of law discussed in thegiven paragraph?(a) This law could not explain the position of isotopes(b) This law proved to be true for elements only up tocalcium.(c) This law could define a total of 9 elements only(d) This law could not define the position of hydrogenAns : (c) This law could define a total of 9 elementsonly18.5Out of A, B and C which element(s) catches firein air?(a) A and B(b) B Only(c) C only(d) B and CAns : (d) B and C19. Read the following and answer any four questionsfrom 19.1 to 19.5.1#4A student of class X wanted to understand thephenomenon of refraction of light through a glass slab.For this, he fix a sheet of white paper on a drawingboard using drawing pins and place a rectangularglass slab over the sheet in the middle. Now, he drawthe outline of slab with a pencil.Using two pins, such that line joining the pins isinclined to edge of slab he look for images through theopposite edge such that images of pins also lie on astraight line and obtained the following ray diagramsas shown below:18. Read the following and answer any four questionsfrom 18.1 to 18.5.1#4In the year 1817, a German chemist, arranged certainelements with similar properties (both physicaland chemical) in groups of three. The basis of thearrangement was the atomic masses of the elements.Download 20 Solved Sample Papers pdf from www.cbse.onlinePage 3

Science X Sample Paper 5 Solvedwww.cbse.online20. Read the following and answer any four questionsfrom 20.1 to 20.5.1#4The magnetic field lines around a straight conductor(straight wire) carrying current are concentric circleswhose centres lie on the wire. It has been shown byexperiments that the magnitude of magnetic fieldproduced by a straight current carrying wire at agiven point is: (i) directly proportional to the currentpassing in the wire, and (ii) inversely proportional tothe distance of that point from the wire.The magnetic field lines are circular near thecurrent carrying circular loop. As we move away,the concentric circles representing magnetic fieldlines become bigger and bigger and at the centre themagnetic field lines are straight.20.1The direction of magnetic field developed arounda current-carrying conductor can be easily foundby the use of:(a) Fleming’s left-hand rule(b) Left-hand thumb rule(c) Right-hand thumb rule(d) Fleming’s right hand rule19.1What is the focal length of a glass slab?(a) Zero(b) One(c) Vary from zero to one (d) InfiniteAns : (c) Right-hand thumb rule20.2The diagram given below represents magnetic fieldcaused by a current-carrying conductor which is:Ans : (d) Infinite19.2In fig. B , the refractive index of medium Brelative to A will be:(a) greater than unity(b) equal to unity(c) zero(d) less than unityAns : (a) greater than unity19.3Refer to fig. A, find the refractive index of mediumB relative to medium A is:(a)26(b)23(c)32(d)62Ans : (c)(a) a solenoid(c) a circular coilAns : (c) a circular coil32We know that,3 /2 n sin i sin 60c sin rsin 45c 1/ 23219.4In one case, the student observes that no refractionof light occurs when ray of light passes frommedium A to medium B . In this case, the anglemade by the ray of tight at boundary of mediumB is:(a) 0c(b) 90c(c) 45c(d) 60cAns : (b) 90c19.5You are given alcohol, mustard oil, glycerine andkerosene. In which of these media a ray of lightincident obliquely at same angle would bend themost?(a) mustard oil(b) glycerine(c) kerosene(d) alcoholAns : (b) glycerine(b) a long straight wire(d) a short straight wire20.3The strength of magnetic field due to a straightconductor depends on the:(a) nature of conductor(b) current passing through the wire(c) direction of current(d) all of aboveAns : (b) current passing through the wire20.4Which of the following correctly describes themagnetic field near a long straight wire?(a) The field consists of straight Lines perpendicularto the wire(b) The field consists of straight lines parallel to thewire(c) The field consists of radial Lines originating fromthe wire(d) The field consists of concentric circles centred onthe wireAns : (d) The field consists of concentric circlescentred on the wire20.5The strength of magnetic field inside a longcurrent carrying straight solenoid is:(a) same at all pointsDownload 20 Solved Sample Papers pdf from www.cbse.onlinePage 4

Science X Sample Paper 5 Solvedwww.cbse.online(i) Milk is made slightly alkaline so that it may notget sour easily.(ii) The alkaline milk takes a longer time to set intocurd because the lactic acid formed has to firstneutralise the alkali present in it.(b) minimum in the middle(c) found to increase from one end to the other(d) more at the ends than at the centre.Ans : (a) same at all pointsSection B21. (i) What is meant by heredity?[2](ii) How many types of genes are there? Name them.Ans :24. Four beakers were taken and marked A, B, C and Drespectively 200 ml of solution of Al 2 (SO 4) 3 in water,CaSO 4 in water, FeSO 4 in water and CuSO 4 in waterwas filled in the beakers A, B, C and D respectively.Clean piece of metal zinc was placed in each solutionand kept undisturbed for two hours.[2](i) The transmission of characters or traits from theparents to their offspring’s is called heredity.(ii) There are two types of genes namely dominantgenes and recessive genes.orWhy did Mendel choose garden pea for his experiments?Ans :Mendel selected pea plant (Pisum sativum) because:(i) These plant are easily available.(ii) They have contrasting characters. The traits wereseed’s colour, pod’s shape, flower’s shape, positionof flower, seed’s shape and plant’s height.(iii) They are self-pollinating.(iv) These plants are easier to maintain.22. List two distinguishing features between sexual andasexual types of reproduction in tabular form.[2]Ans :Difference between sexual and asexual reproduction:Basis .Numberparents2.Reproductive Special organs for Special organsorgansreproductionare reproductionnot required.required.(a) What colour change would you observe in beakerD?(b) Arrange the metals Zn, Al, Ca, Fe and Cu in theorder of decreasing reactivity.Ans :(a) In beaker D , zinc would displace copper fromcopper sulphate solution (blue) to form zincsulphate which is colourless.(b) Ca Al Zn Fe Cu is the order of reactivity.25. A student performs an experiment in the lab to studyimage formation by different types of lenses. Whena fork is seen through lenses A and B one by one, itappears as shown in the above figures.of Sexual reproduction Asexual reproductioninvolvestwo requires only oneindividuals.individual.forare23. (i) What happens when an acid reacts with a metalcarbonate? Give chemical equation involved.(ii) Which gas is usually liberated when an acid reactswith a metal.[2]Ans :(i) When an acid reacts with a metal carbonate, asalt, carbon dioxide and water are formed.Metal carbonate Acid Salt Water Carbon dioxidee.g. ZnCO 3 2HCl ZnCl 2 H 2 O CO 2(ii) Hydrogen gas is usually liberated when an acidreacts with a metal.or(a) What is the nature of lens A? Give reason foryour answer.(b) What is the nature of lens B ? Give reason foryour answer.[2]Ans :(a) The nature of lens A is concave because suchdiminished image is observed when an object neara concave lens.(b) The nature of lens B is convex because suchenlarged image is observed when an object isplaced between the lens and focus of a convexlens.26. A circuit is shown in the diagram given below.A milkman adds a very small amount of baking sodato fresh milk.(i) Why does he shift the pH of the fresh milk from 6to slightly alkaline?(ii) Why does this milk take a long time to set ascurd?Ans :(i) Find the value of R .Download 20 Solved Sample Papers pdf from www.cbse.onlinePage 5

Science X Sample Paper 5 Solvedwww.cbse.online(ii) Find the potential difference across to terminalsof the battery.[2]Ans :(i) Potential difference,PD across 6 Ω 12 VHence, current through 6 Ω ,I V 12 2 A6RSince, R and 6 Ω are connected in series, therefore,the current through R will be 2 A. According toOhm’s law,R V 6 3Ω2I(ii) Potential difference across the terminals of thebattery,V V1 V2 6 12 18 VSection C27. Complete the following flow chart as per the given [3]nitrogenous wastes.(iii) Blood Vessels: They (arteries, veins, andcapillaries) carry blood either away from the heartto various organs or from various organs back tothe heart.28. State in brief two ways in which non-biodegradablesubstances would affect the environment. List twomethods of safe disposal of the non-biodegradablewaste.[3]Ans :The ways in which the environment gets affected bythe non-biodegradable wastes are:(i) Accumulation of non-biodegradable waste mayaccumulate in the environment and concentratein the food chain, thereby harming the organisms.(ii) Non-biodegradablesubstancesmaycausepollution in the soil and increase soil temperature.Two methods of safe disposal of non-biodegradablewastes are:(a) Recycling : The wastes should be treated toextract some valuable materials for reuse.(b) Incineration : Medical and toxic wastes shouldbe burnt at high temperature in incineratorswhich transform the waste into ashes.29. ‘The chromosomal number of the asexually producingparents and their offspring is the same.’ Justify thisstatement.[3]Ans :Ans :TypesFunctions(a) Arteries(d) Carry oxygenated bloodfrom heart to variousorgans of the body.(b) Veins(e)Carry deoxygenated bloodfrom various organs toheart.(c) Capillaries(f)Exchange of materialsbetweenbloodandsurrounding cells takesplace in the capillaries.orWhat are the components of the transport systemin human beings? What are the functions of thesecomponents?Ans :The main components of the transport system in thebody of human are given as follows:(i) Heart: It acts as pump to transport oxygenatedblood throughout the body. It receivesdeoxygenated blood from the various body partsand sends this impure blood to the lungs foroxygenation.(ii) Blood: It is a fluid connective tissue, which helpsin transportation of oxygen, nutrients, CO 2 andIn asexually reproducing organisms, only one parent isinvolved. The part of the body which develops into anew organism contains cells having the same numberof chromosomes as any other cell in the body of theorganism. This separated part develops and forms anew organism.For example, human being somatic cells contain46 chromosomes. When gametes are formed, theycontain half the number i.e., 23 chromosomes butwhen gametes fuse to form the zygote, they maintainthe 46 chromosomes.In sexually reproducing organisms, the parents arediploid (2N) as each of them is having 2 completesets of chromosomes. They form haploid (N) maleand female gametes by the process of meiosis. Thehaploid gamete has one set of chromosomes since,these gametes fuse during fertilisation and restore theoriginal number of chromosomes in the offspring.30. (i) Study the fol

Science X Sample Paper 5 Solved www.cbse.online CLASS X (2020-21) SCIENCE (CODE 086) SAMPLE PAPER-5 Time : 3 Hours Maximum Marks : 80 General Instructions : (i) The question paper comprises

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