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Class 10 CBSE Pre Board 2015 : Science 2 (Kendriya Vidyalaya (KV) No. 2, Raipur)

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SUMMATIVE ASSESSMENT II 2014-15 SUBJECT- SCIENCE CLASS- X Time : 3.00Hrs. 90 Max. marks : Instructions. i) This question paper has two sections A and B . Both the sections are compulsory. ii) Question numbers 1to3 of section A are one mark questions and are to be answered in one word or sentence. iii) Question numbers 4to7 of section A are of two marks questions and are to be answered in two or three sentences or not more than thirty words. iv) Question numbers 8 to19 of section A are of three marks questions and are to be answered in three or four sentences or not more than fifty words. v) Question numbers 20 to24 of section A are of five marks questions and are to be answered in four to five sentences or not more than seventy words. vi) Section B comprises of PBQs. Question number25to 27 a re short answer type questions each carrying two marks . vii) Question number 28 to 36 are multiple choice type questions each carrying one mark. viii) Draw neat and labeled diagrams wherever necessary. SECTION-A Q1. Name the metal which is best reflector of light. Q2. What are the basic events in evolution? Q3. Name the phenomenon of light responsible for Red colour of the sun at sun rise or sun set. Q4. What are inherited traits .Give two examples. Q5. Expand UNEP. Write its significance. Q6.Write the structural formula and Name of the following a) Third member of alkene series. b) A carboxylic acid with 4 carbon atoms. Q7. a) A girl standing in front of a magic mirror observe the image of her legs smaller and that of her head enlarged. Name the type of mirrors combined at the top and bottom b) Which mirror is used in vehicle as rear view mirror and why.Give two reason s. Q8. An element X belongs to group 5 and element Y belongs to group 2 of the periodic table. a)Write the valency and number of valence electrons of element Xand Y. c) Write the formula of the oxides of element X and Y . Q9. Why did Mendel select garden pea plant for his experiment. Q10. An object of height 8cm is placed at a distance of 20 cm in front of a concave lens of power - 4Dioptre. Find the position, nature and size of the image? Q11. A two carbon atom containing neutral organic substance X react with sodium hydrogen carbonate and evolve a gas which burn with a pop sound .Another organic compound containing two carbon when react with sodium hydrogen carbonate evolve a gas which turn lime water milky.When X and Y are heated together in presence of concentrated Sulphuric acid a sweet smelling compound Z is formed. a) What is compound X. Write its molecular formula. b) Identify compound Y and Z. c) Write the chemical equation for the reaction between X and Y top form Z. Q12. Define speciation. What factors are responsible for speciation. Q13. An object is placed 20 cm in front of a spherical mirror . If the image is formed at 4 cm to the behind the mirror , calculate its focal length . Is the mirror convex or concave . What is the nature of the image? Q14.Sneha overheard her grand mother saying to her mother to give birth to a male child at least this time otherwise she would be in trouble. Her mother was sad. Sneha told her gand mother that her mother cannot decide the sex of the inborn baby and explained the mechanism of sex determination to her grandmother. a) What values are displayed by Sneha. b) Who is responsible for determination of sex of inborn baby ? Explain how. Q15. Aditya observed that his mother is throwing all types of waste generated at home in a common dustbin. He suggested his mother to sort out the waste and dispose them separately. a) What values are displayed by Aditya? b)Why did Aditya ask his mother to sort out the waste and dispose them separately? c) How can we reduce the generation of waste at home ? Q16.a) Draw a labeled diagram of human eye. b) Who could not donate their eyes after death? Q17.How is sexual reproduction different from asexual reproduction. Give atleast three points of difference. Q 18. Dharam singh when returned to his village after 10 years amazed to see yhe trees in the forest are wilting (drying) and the forest is on the verge of destruction. He observed that every farmer has two bore wells in their field and are growing water intensive crops. He advised the people of his village to construct check dams across the flooded gullies. a) Why are the trees in the forest wilting? b) State any two purpose of building check dams . c) Write two advantages of underground storage of water. Q19a). Write an activity to show that sunlight consists of seven colours. b) What phenomena of light are responsible for formation of rainbow? c) Why do the sky appear blue? Q20.Rani and Ananya are best friends. Rani suggested Ananya to use mechanical barrier contraceptive and take her husband to a doctor for blood checking as her husband was unable to recover from illness. The doctor prescribed ELISA test for Ananya s husband. a) b) c) d) e) What values are displayed by Rani? What does positive of ELISA test confirm? Write the two advantages of using mechanical barrier contraceptive. Expand STDs. Name two viral STDs. How can STDs be prevented? Q21. What is denatured alcohol? Why is alcohol denatured? Write any four uses of Ethanol. Write any two harmful effect of alcohol consumption in human beings. Q22 . Mohan and Ramesh are good friends. Ramesh noticed that Mohan is unable to read the small letters on the black board from some distance. He suggested his friend to consult an ophthalmologist .Mohan consulted the ophthalmologist who prescribed him spectacles fitted with lense of certain focal length. a) What values of Ramesh do you appreciate? b) What is the defect eye Mohan suffering from? Write the cause of the defect? c) What type of lens might have been prescribed by the ophthalmologist? d) Draw a ray diagram illustrating the defect of eye and its remedy. Q23. An element X is an important constituent of our food. It forms two types of Oxides viz. XY and XY2 The oxide XY2 causes global warming where as the oxide XY is poisonous. a) Identify XY2 and XY. b) Name the element X. To which group of the periodic table does it belong ? c) What type of bond does element X form and why? d) Explain two peculiar properties of this element. Q24. a) Illustrate fertilization in flower with the help of labeled diagram. b) Differentiate between pollination and fertilization .(any two points ) SECTION-B Q25. Differentiate between homologous and analogous organs with examples. Q26. a) Explain how would you differentiate between hard water and normal water at home. b) What makes the water hard? Q27. a) Define Snell s law. b) Find the angle of incidence when the incident ray makes an angle of 30 at the point of incidence and angle of refraction is 45 . Q28. The chemical substance added for precipitation of soap is a) Sodium hydroxide b) Sodiumhydrogencarbonate c) Sodium chloride d) Sodiumcarbonate. Q29. The image of a tree has a diminished size when seen in a mirror from a close distance .The mirror is a) Concave b) convex c) plane d) None of these Q30. On tracing the path of a light ray passing through rectangular glass slab , which one of the following is the correct statement: a)Angle of incidence is greater than angle of emergence b) Emergent ray is parallel to the incident ray. c) angle of emergence is less than angle of refraction . d) Emergent ray is parallel to refracted ray. Q31. Which one of the following diagram represent the refraction of light through prism correctly Q32. Spore formation is commonly not found in a) Ulothrix b)Bacteria c) Mucor d) HIV Q33. The correct labeling of the diagram is a) cotyledon,plumule, radicle b) Radicle, Plumule, Cotyledon c) Plumule, Radicle, Cotyledon d) Cotyledon, Radicle, Plumule Q34. Four students tabulated their observation as given below Student Color of acetic Odour Reaction with NaHCO3 acid I Colourless Rotten Egg Effervescence II Pale yellow Fruity Smell Gas evolved without bubbles III Colourless Pungent Effervescence IV Light Blue Odourless Gas evolved with bubbles. The correct set of observation is that of student a)I b) II c) III d) IV Q35. Four Students placed the protractor for measuring the angle of incidence .The student who placed the protractor in correct manner is Q36 A student was given a slide with many Amoeba . He was asked to focus on the Amoeba undergoing binary fission . The student will focus on a) A rounded Amoeba with a round nucleus. b) An Amoeb with elongated nucleus and a constriction in the middle. c) An Amoeba with small nucleus and many pseudopodia. d) An Amoeba with food vacuole and round nucleus. Key and Marking scheme Q1. Silver Q2. Changes in DNA. 1M 1M Q3. The red light is scattered less, and more red light reach the observer. 1M Q4.Features or characters that are transferred from parent to offspring. Eg: eye colour, earlobes, blood types etc. 1+1=2 M Q5.United Nations environment programme. Succeeded in forging an agreement to freeze CFC production ,phasing out of ozone depleting substances and helping developing countries to implement use of alternatives of CFCs. 1+1=2M H H H Q6.a) H -C C =C H PROPENE 1/2x2=1M H H H H b) H C C C C- OH Butanoic acid 1/2x2=1M H H H Q7. Concave at the top and convex at the bottom concave mirror . 1/2x2=1M Concave mirror forms enlarged and virtual image. convex mirror forms diminished and virtual image.1x2=2M Q8. a) the group no gives the no. of valence electrons .Therefore Valency of element X is 8- 5=3 and number of valence electrons is 5 and the valecny of Y is 2 and the no. of valence electrons is 2 . 1/2x4=2M b) Oxide of element X is XO3 and that of Y is YO .1/2x2=1M Q9. I) Garden pea plant is self fertilizing. Over generations self fertilization help to obtain pure line with constant traits ii) .It is easily cultivated and took only one growing season from one generation to the next . iii) Garden pea has many sharply defined inherited contrasting traits of the character. iv). Flowers are bisexual and cross pollination cane easily be achieved. ( anythree points ) 3x1=3M Q10. ho =8 cm P=1/f m P= -4D u= -20 cm f= 100/p cm f=100/-4 cm 1/f= 1/v- 1/u 100/9cm 1/v=1/f + 1/u hi / ho = v/u f=-25cm 1/v=-1/25- 1/20 1/v= -9/100 hi / 8cm =100/9 x1/20 v=- hi = 40 cm Position of the image is 100/9=11.1 cm Nature of image is vitual and erect Image size = 40 cm 3x1=3M Q11. A) X is Ethanol molecular formula is C2 H5 OH 1M b) Y is Ethanoic acid and Z is Ethylethanoate 1/2+1/2=1M Conc.H2 SO4 c) CH3 COOH + C2 H5 OH CH3 COO C2 H5 1M Q12. A) Origin of new species from pre existing species. 1M b) Fcators : Explanation of Reproductive Isolation , genetic drift, and Natural selection. (any two factors ) 2M Q13. U = - 20cm v = 6 cm ( since the image is formed behind the mirror) F=? 1/f = 1/v + 1/u 1/f= 1/4 - 1/20cm 1/f = 5-1/20 f= 5cm 2M Since f is positive the mirror is convex. Since the image is formed behind the mirror it is virtual and erect. + = 1M Q14. A) Sneha displays scientific aptitude ,concerned. 1M b) Human beings have 25 pairs of chromosomes. Out of which 22 pairs are autosomes and one pair is sex chromosomes. The autosomes are similar in both male and female but the sex chromosomes are XY in Male and XX in female. Thus Male produces sperms of two types one containing X and the other containing Y chromosome .Female produces ova of same kinds containing X chromosome only. If sperm containing X chromosome fertilizes the ovum ,the offspring produced is female. If the sperm containing Y chromosome fertilizes ovum male offspring is produced. 2M. Q15.a) Aditya shows concern for environment. Awareness 1M b) Some wastes are biodegradable and some are non biodegradable. If the non biodegradable wastes are disposed separately they can be easily recycled otherwise they cause environmental pollution . 1M c) By 3 R approach ( Reduce Reuse and Recycle ) 1M Q16. a) Labeled diagram 2M b) People suffering from diseases such as AIDS, Hepatitis B etc. cannot donate their eyes after death. 1M Q17. Sexual reproduction Asexual reproduction i) Two parents of different sex are involved i) Single parent is involved ii) Daughter individual are genetically different from parent s ii) Daughter individual are genetically identical to parent s iii) It involves fusion of gametes produced by reproductive parts. iii) It involves vegetative part of the parent. 3x1=3M Q18.a)The trees are wilting because the ground water table has declined due to which roots are not getting water. 1M b) (1) Check dams help to recharge the ground water. 1/2x2=1M (2) Reduces run off lose and avoid flooding. c) (1) It is relatively protected from contamination by human and animal wastes. (2) It does not evaporate, does not provide breeding ground for mosquitoes. 1/2x2=1M Q19. Take a thick sheet of cardboard and make a narrow slit in its middle allow the sun light to fall on the narrow slit take a glass prism and allow light from the slit to fall on one of its faces turn the prism slowly until the light that comes out of it appears on a nearby screen. We get spectrum of seven colour appears on screen. Now place another identical prism in an inverted position with respect to the first prism so that all the colors of the spectrum pass through the second prism. Abeam of white light emerge from the other side of the second prism. 2M. b) Refraction , dispersion and internal reflection 1M c) The wave length of blue color light is smaller than the red color light. Therefore the intensity of the scattered blue light is larger than that of red light. The tiny particles present in the atmosphere scatter blue light as their size is less than the wave length of blue light. 2M. Q20. Rani shows scientific aptitude, aware of AIDS ,good friend, concerned. 1M b) Confirm infection of HIV. 1M c) avoid pregnancy, Safeguard from STDs 1\2x2=1 m d Sexually transmitted diseases. Warts , AIDS, Hepatitis B. (any two) 1/2x2=1 M e) personal hygiene, use of mechanical barriers, safe and protected sex, in case of infection medical treatment should be taken immediately.(any two ) 1/2x2=1 M Q21. A) Ethanol to which certain poisonous and nauseating substances like methanol/ pyridiene / copper sulphate etc. is added to make it unfit for drinking is called denatured alcohol. 2M b) Ethanol is denatured to prevent its misuse for drinking purpose. 1M c)i) Consumption of alcohol for long time damage the liver and stomach and even brain. ii) consumption of alcohol slows down the activity of CNS and brain lead to lack of coordination, mental confusion and drowsiness. 1x2=2 m Q22. Q11. Ramesh is aware of defects of eye .scientific aptitude, good friend. 1M b) Myopia . Causes i) Increase in curvature of lens. ii) elongation of eye ball. 1/2x2=1 M c) Concave lens of appropriate focal length or power 1M d) Correct diagrams 1+1 M Q23. a) X Y2 is Carbondioxide and XY is carbonmonoxide. 1/2x2=1 M b) Element X is Carbon It belong to 14 group of periodic table . 1M c)It forms covalent bonds. 1M d) explanation of Catenation and tetravalency 1x2=2 M Q24. A) Labeled diagram 2M b) Poolination ,pollen tube germination, fusion of gametes and double fertilization should be explained. 2M c) any two differences 1/2x2=1 M Q25 Homologous organs have similar origin and structure but perform different functions. Example : fore limbs of man, horse and birds.1M Analogous organs have different origin and structure but perfom similar functions. Example: Wings of bat and birds. 1M Q26. By dissolving soap in the given sample of water we can differentiate between hard and normal water. The water which give rich lather with soap is normal water. The water which shows formation of scum with soap is hard water. The presence of Magnesium and /or calcium ions make water hard. 1x2=2M Q27 Snell s Law state that the ratio of sine of angle of incidence and sine of angle of refraction is a constant. b) Angle of incidence = 90-30 = 60 . Q28 c Q29 b Q30 b Q31 d Q32 d Q33 c Q34 c Q35 d Q36. b

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