Sample Paper Class 10 Science - Studymate

1. Sample Paper (2018-19) Date: ____________ Duration : 3 Hrs. Max. Marks : 80 Class X General Science Instructions: (i) The question paper comprises of five sections – A, B, C, D and E. You are to attempt all the sections. (ii) All questions are compulsory. (iii) Internal choice is given in sections B, C, D and E. (iv) Question numbers 1 and 2 in Section-A are one mark questions. They are to be answered in one word or in one sentence. (v) Question numbers 3 to 5 in Section- B are two marks questions. These are to be answered in about 30 words each. (vi) Question numbers 6 to 15 in Section-C are three marks questions. These are to be answered in about 50 words each. (vii) Question numbers 16 to 21 in Section-D are 5 marks questions. These are to be answered in about 70 words each. (viii) Question numbers 22 to 27 in Section- E are based on practical skills. Each question is a two marks question. These are to be answered in brief. Section – A 1. 2. Name the muscle that regulates the movement of food from stomach to small intestine. Who is known as the 'Water man of India' and why? [1] [1] Section – B 3. 4. What is Thermite reaction? Mention its application. What are fossils and explain how fossil records provide us an evidence in favour of evolution? What are the factors on which refractive index of a medium depends? OR Draw a ray diagram to show the path of reflected ray when incident ray falls on a concave mirror, parallel to its principal axis. [1+1] [2] [2] 5. [2] Section – C 6. (a) (b) Why do we store silver chloride in dark colored bottles? 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? [1½] [1+½] [1]

2. ) 7. Identify the compound X on the basis of the reactions given below. Also, write the name and 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] A quiz contest was being held in the school for chemistry students. The quiz-master said: An element has the electronic configuration 2, 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? (a) ‘‘It is a matter of chance whether a couple will have a male or a female child.’’ Justify this statement by drawing a flow chart. (b) For which characteristics did we artificially make Cabbage and Cauliflower from the wild cabbage? 10. (a) Trace the sequence of events through a reflex arc which occurs when a bright light is 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. 11. The Image of a candle flame placed at a distance of 45 cm from a spherical lens is formed on a screen placed at a distance of 90 cm from the lens. Identify the type of lens and calculate its focal length. If the height of the flame is 2 cm, find the height of its image. 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: (a) between optical centre (O) and principal focus (F) of a convex lens. (b) at 2F of a convex lens. 12. (a) How will you connect 3 resistances, each of 2 ohms,so that effective resistance is that of 3 ohms? Draw a circuit diagram depicting your connection. (b) State Joule's Law of heating. 13. A 100 watt electric bulb is lighted for 2 hours daily and four 40 watt bulbs are lighted for 4 hours every day. Calculate the electrical energy consumed in kWh in 30 days. 14. (a) Mention the main constituents of biogas along with its percentage. (b) What are the limitations of harnessing wind energy? 15. (a) What is the role of bacteria in an ecosystem? (b) What is biological magnification? (c) Why is the flow of energy in an ecosystem always unidirectional? 8. 9. [3] [2+1] [2+1] [3] [1.5+1.5] [2+1] [3] [1] [2] [1+1+1] [2]

3. Section – D 16. (a) A, B and C are three elements which undergo chemical reactions in the following way: (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? Show the formation of Na2O by the transfer of electrons. What is Homologous series? Name the 2nd and 3rd homologue in the homologous series of Alcohols. Give reasons for the following:- (i) Unsaturated hydrocarbons show addition reactions. (ii) Conversion of ethanol to ethanoic acid is an oxidation reaction. 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. When do the desert plants take-up carbon dioxide and how do they perform photosynthesis? 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 Differentiate between Mustard and Papaya flower. Mention any two changes that take place in a flower after fertilization. Label all the parts given in the diagram below and give the function of part B and D. [1½+1½] 17. (a) (b) [2] [1+1] 18. (a) 19. (a) (b) [3] (b) (c) [1+1+3] [1+1+3] (b) (c) OR (a) (b) (c) How do variations arise in an individual organism and how is it advantageous to them? 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. Which fertilization is advantageous to an organism and why? [2+2+1] [3]

4. 20. (a) Why do stars twinkle while planets do not? A person needs a lens of power -4.5D for correction of her vision. [2] (b) [3] 21. (a) (i) (ii) (iii) What is electromagnetic induction? Also state the rule which is closely related to this. With the help of a labelled diagram, explain the distribution of magnetic field due to a current through a circular loop. An electron moving in the upward direction deflects toward left in a magnetic field. Find the direction of magnetic field. OR Draw the pattern of magnetic field lines through and around a current carrying solenoid. AB is a current carrying conductor in the plane of the paper as shown in the figure. (i) What are the direction of magnetic field of magnetic fields produced by it at points P and Q? (ii) Given r1 > r2, where will the strength of the magnetic field be larger? What kind of defect in vision is she suffering from? What is the focal length of the corrective lens? What is the nature of the corrective lens? (b) (c) [2+2+1] (a) (b) (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? 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. 23. A student adds a spoon full of powdered sodium hydrogen carbonate to a flask containing ethanoic 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 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) What would happen if a thermometer is kept in the conical flask with the germinating seeds? 25. Draw a neat labelled diagram of Binary fission in Amoeba. 26. (a) While experimentally verifying Ohm's law, a student observed that the pointer of the voltmeter coincides with the 15th division. When the voltmeter has the least count of 0.05 V, find the observed reading of voltmeter. (b) What is likely to happen if we pass the current for a longer time in the circuit in Ohm's law experiment? [2] [2] [2] [2] [1+1] [4]

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. OR Refractive indices of media A, B, C and D are given below: [2] Medium A B C D Refractive Index 1.33 1.44 1.52 1.65 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. vvvvv [5]

6. Hints/Solutions to Sample Paper (2018-19) Date: ____________ Duration : 1 Hr. Max. Marks : 30 Class X General Science 1. 2. Sphincter muscle that regulates the movement of food from stomach to small intestine 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. 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. Fe2O3(s) + 2Al(s) → 2Fe(l) + Al2O3(s) + Heat 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. 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 of the substance will affect the refractive index. The index is also influenced by the permeability of the material. OR 3. [1+1] 3. 5. [2] [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. Sunlight  →  2Ag (s) + Cl2 (g) 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. Reaction of bases with metals : (1) 2NaOH+ Zn → Na2ZnO2 + H2(g) Sodium Zincate (2) NaOH + HCl → NaCl + H2O (3) NaOH + CH3COOH → CH3 COONa + H2O So A = Na2ZnO2 B = NaCl C = CH3 COONa 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. D Na2CO3 + H2O + CO2 Washing soda is used in glass, soap and paper industries. (a) Atomic number = 17 (b) F - as it belongs to the same group as the element(Cl) [0.5+1] 2AgCl (s) (b) 7. [1+0.5] [1+1+1] [1] 8. 2NaHCO3 [1] [1]

7. 9. (d) (a) CaCl2 or MgCl2 causes temporary hardness of water. [1+1+1] 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. Cabbage – Very short distances between leaves Cauliflower – For sterile flowers Stimulus(Light) → Photoreceptor in eye → Sensory Neuron → Relay Neuron (CNS) → Motor Neuron → Eye (Effector Organ) → Eye is shut (Effect) (i) Pancreas (ii) Adrenal Gland 10. (b) (a) 11. (b) Given: Object distance u = −45 cm Image distance v = 90 cm The image of a candle flame is formed on the screen, so a convex lens is used. 1 f 1 f 1 f 1 f 1 v 1 u = − 1 90 1 90 1 90 1 30 1 45 − 1 45 3 90     = − = + + 2 = + 1 f = \ Hence, it is a convex lens of focal length 30 cm. Height of the flame (object) h1 = 2 cm h h u 1 2 90 45 45 − h2 = –4 cm Height of image h2 = −4 cm Thus, the height of the image is 4 cm. The minus sign indicates that the image is formed below the principal axis. Thus, the image is real and inverted. OR f = 30 cm v Magnification m = = 2 × 180 = = − h2 [1+1+1] [1.5] [7]

8. [1.5] 12. (a) It is given that effective resistance is 3 ohms So 3 = 2 + 1 two resistors must be connected in parallel to another resistor in series. 3W = 1W + 2W 1 2 1 2 Ω = Ω + Ω 1 . So the connection would be like. R2 2W R1 R3 2? 2? [1+1] ‘X’ V R (b) Joules Law states that when current I flow through a resistor of electric resistance R, heat is produced. The heat produced H depends directly on the square of the current, resistance and time t for which the current is allowed to pass. H = I2 Rt, SI unit Heat energy: joule Energy consumed by electric bulb = P × T Energy consumed by electric bulb of 100 w = 100 w × 30 × 2 hrs Energy consumed by electric bulb of 100 w = 3000 watt-Hr Energy consumed by electric bulb of 100 w = 3 kilo watt-Hr Energy consumed by four bulbs each of 40 w = Number of the bulbs × power of each bulb × Time Energy consumed by the four bulbs = 4 × 40 w × 4 hrs ×30 Energy consumed by the four bulbs = 19200 watt-Hr Energy consumed by the four bulbs = 19.2 kilowatt-Hr Total energy consumed = Energy consumed by electric bulb of 100 w + Energy consumed by four bulbs each of 40 w Total energy consumed = 3 kilo watt-Hour + 19.2 kilowatt-Hour Total energy consumed = 22.2 kilo watt-Hour (a) Methane CH4: 50–75% Carbon dioxide CO2: 25–50% Nitrogen N2: 20–10% Hydrogen H2: 0–1% Hydrogen sulfide H2S: 0–3% Oxygen O2: 0–0.5% (b) The limitations in harnessing wind energy are- 1. The speed of wind must be high (min. 15km/h) 2. Cost of setting up a wind farm is high 3. Availability of land as per the requirements i.e. large lands in hilly regions with high speed wind. [1+1] (a) The bacteria help in cleaning the ecosystem and cyclic flow of nutrients in the ecosystem. (b) The increase in concentration of harmful chemical substances like pesticides in the body of living organisms at each trophic level of a food chain is called biological magnification. (c) The flow of energy is unidirectional. The energy that is captured by the autotrophs does not revert back 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. ??? (a) Homologous series is a series of compounds with the same functional group and similar chemical properties in 13. 14. 15. [1] [3] [1] 16. 17. [8]

9. which the members of the series differ by the number of repeating units they contain. 2nd and 3rd homologue of alcohol: ethanol and propanol (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. (ii) CH3CH2OH + (Alkaline KMnO4) → CH3COOH Since, in this reaction one oxygen is added to ethanol, hence it is an oxidation reaction. (i) Renal artery (ii) Renal vein Desert plant take in carbon dioxide at the night and convert it into an intermediate product and convert it into glucose in the day. [1+1] (b) [1.5+1.5] 18. (a) (b) (c) [1+2] 19. (a) Mustard flower Papaya flower It is a bisexual flower having both the sex organs i.e. stamen and pistil, in the same flower. Any two changes that take place in a flower after fertilization are the ovary develops into a fruit and sepals, petals and stamen dry and fall off. A – Pollen grain B – Stigma 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 The replication of DNA in the cell is done by certain biochemical reactions which synthesize more of genetic material. No biochemical reaction can produce 100% same results. These slight variation in the replication of DNA 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. (i) Scrotum (ii) Epidydimus (iii) Placenta Internal fertilization is advantageous to the organism as the development of the embryo takes places in protected environment thus ensuring better survival probability. 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. (i) She is suffering from myopia (ii) f = – 22.22 cm. (iii) It is a concave lens. The process by which a changing magnetic field in a conductor induces a current in another conductor is called electromagnetic induction. Fleming’s Right-hand Rule: Stretch the thumb, forefinger and middle finger of your right hand such that they are mutually perpendicular. If the forefinger points in the direction of the magnetic field and the thumb in the direction of motion of conductor, then the middle finger will point in the direction of the induced current. It is a unisexual flower having only one sex organ either stamen or pistil in a flower. (b) (c) C – Pollen tube D – Female gamete (a) (b) (c) (iv) Menstruation 20. (a) [2] 21. (b) (a) [1+1+1] [2] [9]

10. (b) [2] (c) Using Fleming's Left-hand Rule: Direction of magnetic field is towards south. [1] OR magnetic line of force axis of magnet axis of magnet N S (a) [2] (b) The directions of magnetic fields produced by it at point P is into the plane of paper and out of paper at point Q. Magnetic field at Q is greater than at P. An electric generator converts mechanical energy into electrical energy. The principle of working of an electric generator is that when a loop is moved in a magnetic field, an electric current is induced in the coil. It generates electricity by rotating a coil in a magnetic field. Brushes of AC generator transfer current from the armature of the generator to the load in the circuit. 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 OR ? Observations: 1. Brisk effervescence 2. Reaction: 2CH3COOH + Na2CO3 → 2CH3COONa + CO2 + H2O. 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) With the help of a filter paper, remove the excess of stain and water. (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) If a thermometer is kept in the conical flask with the germinating seeds the temp in the thermometer shows a rise as aerobic respiration releases some amount of energy too. (i) [2] (c) (ii) [1] 22. [1+1] 23. 24. Sodium salt formation [10]

11. 25. 26. (a) (b) 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 = 0.05v and the pointer (n) is at 15th division. Therefore, the observed reading of the voltmeter = 0.05 × 15 = 0.75 volts. As we know according to ohms law, v = IR, where – v – potential difference I – current R – Resistance 1 R I a resistance decrease. So, if we pass current for a long time the value of resistance decreases. The pin should be fixed on vertical position and all pins should be placed in straight line. Angle of incidence should be lies between 30° to 60° . , it shows that current is inversely proportional to resistance that is as we increase the current the 27. 1. 2. 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. Speed of light is minimum in D as it has more refractive index. Refractive index the ratio of the velocity of light in a vacuum to its velocity in a specified medium. vvvvv [11]