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CBSE Class 10 Board Exam 2025 : Science

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Series: 1GEFH SET-2 Q.P.Code 31/1/2 Roll No. Candidates must write the Q.P. Code on the title page of the answer-book. NOTE 271 (II) 9A-47 aIfa E f 3N fu r Please check that this question paper contains 27 printed pages. iI) Q.P. Code given on the right hand side of the question paper should be written on the title page of the answer-book by the candidate. (III) 4T ig fA S4 YH-47 39 SNH III) Please check that this question paper contains 39 questions. (IV) a4T NYT GhT 3R foGHT A h IIV) Please write down the Serial Number of the question in the answer-book at the given place before attempting it. 15 minute time has been allotted to 10.15 f read this question paper. The question paper will be distributed IqT | 10.15 q at 10.15 a.m. From 10.15 a.m. to 10.30 a.m., the candidates will read the question paper only and will not write any answer on the # answer-book during this period. SCIENCE 3yfech4 3j% : 80 Timeallowed : 3 hours *31/1/2* Maximum Marks : 80 1) [P.T.0. ) GeneralInstructions : Read the following instructions very carefully and strictly follow them : (i) This question paper comprises 39 questions. ALl questions are compulsory. (ii) This question paper is divided intofive sections - A, B, C, D and E. ( i) Section A - Questions No. 1 to 20 are Multiple Choice Questions. Each (iv) question carries 1 mark. Section B - Questions No. 21 to 26 are Very Short Answer type questions. Each question carries 2 marks. Answer to these questions should be in the (v) rangeof 30 to 50 words. Section C - Questions No. 27 to 33 are Short Answer type questions. Each question carries 3marks. Answer to these questions should in the range of 50to 80 words. (vi) Section D - Questions No. 34 to 36 are Long Answer type questions. Each question carries 5 marks. Answer to these questions should be in the range of 80to 120words. (vi) Section E - Questions No. 37 to 39 are of 3 source-based / case-based units of assessment carrying 4 marks each with sub-parts. (ui) There is no ouerall choice. However, an internal choice has been provided in some sections. Only one of the alternatives has to be attempted in such questions. SECTION A Selet and write the most appropriate option out of the four options given for each of the questions no. l to 20. There is no negative marking for incorrect 20x1=20 response. 1. The formation of magnesium oxide is correctly shown in option: (A) Mg:C: Mg2:0:] (B) Mg"-0: Mgt : : (C) Mg (D) *31/1/2* [P.T.0.] 2. The metals obtained from their molten chlorides by the process of electrolytic reduction are : (A) (B) (C) (D) 3. 4. Gold and silver Calcium and magnesium Aluminium and silver Sodium and iron In one formula unit of salt X, seven molecules of water of crystallisation are present. The salt Xis: (A) CuSO4 (B) NaCO3 (C) FeSO4 (D) CaSO4 Reaction between two elements A and B, forms a compound C. A loses electrons and B gains electrons. Which one of the following properties will not be shown by compoundC? (A) It has high melting point. (B) (C) (D) 5. It is highly soluble in water. It has weak electrostatic forces of attraction between its oppositely charged ions. It conducts electricity in its molten state or aqueous solution. Electrolysis of water is a decomposition reaction. The mass ratio (My : Mo) of hydrogen and oxygen gases liberated at the electrodes during electrolysis of water is : 6. (A) 8:1 (B) 2:1 (C) 1:2 (D) 1:8 Consider the following reactions : i) Dilute hydrochloric acid reacts with sodium hydroxide. Magnesium oxide reacts with dilute hydrochloric acid. (ii) Carbon dioxide reacts with sodium hydroxide. (ii) It is found that in each case: (B) (C) Salt and water is formed. Neutral salts are formed. Hydrogen gas is formed. (D) Acidic salts are formed. (A) *31/1/2* 5 [P.T.0.] 7. The products formed when Aluminium and Magnesium are burnt in the presence of air respectively are: (A) (C) 8. Al,04 and MgO, Al,04 and MgO (B) Al,0, and MgO (D) Al,0, and MgO, The plant hormone whose concentration stimulates the cells to grow longer on the side of the shoot which is away from light is: (A) Cytokinins 9. 10. (B) Gibberellins (C) Adrenaline (D) Auxins Secretion of less salivain mouth will effect the conversion of: (A) proteins into amino acids (B) (C) fats into fatty acids and glycerol starch into simple sugars (D) sugars into alcohol If pea plants with round and green seeds (RRyy) are crossed with pea plants having wrinkled and yellow seeds (rrYY), the seeds developed by the plants of F; generation will be: 11. (A) 50% round and green (B) 75% wrinkled and green (C) 100% round and yellow (D) 75% wrinkled and yellow The correct/true statement(s) for a bisexual flower is/are: (i) They possess both stamen and pistil. (ii) They possess either stamen or pistil. (iii) They exhibit either self-pollination or cross-pollination. (iv) They cannot produce fruits on their own. (A) (i) only (B) (iv) only (C) (i) and (iii) (D) (i)and (iv) *31/1/2* 7 # P.T.0.] 12. The breakdown of glucose has taken the following pathway : Glucose (a) Pyruvate + Energy (b) Lactic acid + Energy The sites 'a' and 'b respectively are: (A) 13. (B) Mitochondria and Oxygen deficient muscle cells Cytoplasm and Oxygen rich muscle cells (C) Cytoplasm and Yeast cells (D) Cytoplasm and Oxygen deficient muscle cells The white light entering a glass prism, gets split into its constituent colours. It is observed that: (A) Red light deviates the most. (B) Violet light deviates the least. (C) Yellow light deviates more than the blue light. Green light deviates more than the orange light. (D) 14. Mirror X is used to concentrate sunlight in solar furnace and Mirror Y is fitted on the side of the vehicle to see the traffic behind the driver. Which of the following statements are true for the two mirrors ? (i) The image formed by mirror X is real, diminished and at its focus. (iv) The image formed by mirror Y is virtual, diminished and erect. The image formed by mirror X is virtual, diminished and erect. The image formed by mirror Y is real, diminished and at its focus. (A) (i) and (ii) (B) (ii) and (ii) (C) (iii) and (iv) (D) (i) and (iv) (ii) (iii) 15. The percentage of solar energy which is not converted into food energy by the leaves of green plants in a terrestrial ecosystem is about : (A) 1% (B) 10% (C) 90% (D) 99% *31/1/2* 9 IP.T.0.] Which of the following groups do not constitute a food chain ? 16. (i) (ii) (iii) (iv) (A) (C) Wolf, rabbit, grass, lion Plankton, man, grasshopper, fish Hawk, grass, snake, grasshopper, frog Grass, snake, wolf, tiger (i) and (iv) (ii) and (iii) (B) (i) and (iii) (D) (ii) and (iv) For Questions number 17 to 20, two statements are given one labelled as Assertion (A) and the other labelled as Reason (R), Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below. (A) (B) (C) (D) 17. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A). Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A). Assertion (A) is true, but Reason (R) is false. Assertion (A) is false, but Reason (R) is true. Assertion (A): A human child bears all the basic features of human beings. Reason (R): It looks exactly like its parents, showing very little variations. 18. Assertion (A): The amount of ozone in the atmosphere began to drop sharply in the 1980s. The oxygen atoms combine with molecular oxygen to form Reason (R): 0ZOne. 19. Assertion (A): Decomposition reactions are generally endothermic reactions. Reason (R): Decomposition of organic matter into compost is an exothermicprocess. 20. Assertion (A): No two magnetic field lines are found tocross each other. Reason (R): The compass needle cannot point towards two directions at the point of intersection of two magnetic field lines. *31/1/2* 11 |P.T.0.] SECTION B Questions no. 21 to 26 are Very Short Answer Type questions. 21. 22. "Excessive use of chemicals and pesticides in agriculture adversely effect the environment." Justify this statement. (a) Consider the following circuits : 2 5 Q 52 (i) (ii) 12 V (i i) 52 5 Q 12 V 5 2 12 V In which circuit will the power dissipated in the circuit be (I) minimum ) maximum ? Justify your answer. 2 OR (b) Two lamps, rated 100 W; 220 V and 60 W; 220 V are connected in parallel to electric main supply of 220 V. Find the current drawn by the two lamps from the supply. 23. 2 An object is placed at a distance of 30 cm in front of a concave mirror of focal length 20 cm. Use mirror formula to determine the position of the image formed in this case. 24, (a) 2 Besides minimising the loss of blood, why is it essential to plug any leak in a blood vessel ? Name the component of blood which helps in this process and state how this component perform this 2 function. OR (b) (i) The transport system in plants is relatively slower than in animals. Give reasons. (ii) *31/1/2* State the role of phloem in the transport of materials in plants. 13 # [P.T.0.] 25. Draw labelled diagrams to show different stages of budding in Hydra. 2 26. What happens when: (write balanced chemical equation) 2 (a) Lead nitrate is thermally decomposed, (b) Natural gas burns in oxygen (or air) ? SECTION C Questions no. 27 to 33 are Short Answer Tpe questions. 27. s ) (b) Define one amnpere. The resistance of a wire of 0-01 cm radius is 14 2. If the resistivity of the material of the wire is 44 x 10- 2m, find the length of the wire. (Given 1 = 28. 7 Consider the following electric circuit : 10 2 15 Q A 15 V= 60 2 K 40Q Calculate the values of the following: (a) The total resistance of the circuit (b) The total current drawn from the source (c) Potential difference across the parallel combination of 10 2 and 15 2 resistors *31/1/2* 15 # |P.T.0. J 29: Draw ray diagrams to show the nature, position and relative size of the image formed by a convex mirror when the object is placed (i) at infinity and (ii) between infinity and polePof the mirror. 30. (a) 3 With the help of an activity, explain the conditions under which iron articles get rusted. 3 OR (b) (i) Name two metals which react violently with cold water. List any three observations which a student notes when these metal are dropped in a beaker containing water. (ii) Write a test to identify the gas evolved (if any) during the reaction of these metals with water. 31. (a) 3 Displacement reactions also play a key role in extracting metals in the middle of the reactivity series." Justify this statement with two examples. (b) Why can metals high up in the reactivity series not be obtained by 3 reduction of their oxides by carbon ? 32 In one of Mendalian experiments, when F, generation pea plants with round yellow seeds were self-pollinated, pea seeds with the following combinations were obtained in F generation : Seeds Number Round Round yellow green Wrinkled yellow 800 275 268 Wrinkled green 90 Analyse the result and describe the mechanism of inheritance of traits which explains the above results. 33. (a) 3 Name the glands that secrete : (i) Adrenaline Thyroxin Explain with example how the timing and amount of hormone (ii) (b) released are regulated in the human body. *31/1/2* 17 3 [P.T.0. ] SECTION D Questions no. 34 to 36 are Long Answer Type questions. (i) 34. The power of a lens X is - 2-5 D. Name the lens and determine its focal length in cm. For which eye defect of vision will an optician prescribe this type of lens as a corrective lens ? (ii) "The value of magnification 'm' for a lens is 2." Using new Cartesian Sign Convention and considering that an object is placed at a distance of 20 cm from the optical centre of this lens, state : (I) the nature of the image formed; (II) size of the image compared to the size of the object; (III) position of the image, and (IV) sign of the height of the image. (iii) The numerical values of the focal lengths of two lenses A and B are 10 cm and 20 cm respectively. Which one of the two will show higher degree of convergence/divergence ? Give reason to justify your answer. 5 OR (b) i) Draw a ray diagram to show the refraction of a ray of light through a rectangular glass slab when it falls obliquely from air into glass. /i1) (iii) State Snell's law of refraction of light. Differentiate between the virtual images formed by a convex lens anda concave lens on the basis of: *31/1/2* () object distance, and (II) magnification. 5 19 [P.T.0.] 35. (a) A saturated organic compound A' with two carbon atoms belongs to the homologous series of alcohols. On oxidation, it forms an organic acid B with molecular mass 60 u. On heating A' with eXcess concentrated sulphuric acid at 443 K, an unsaturated hydrocarbon C' is formed. (i) Name A, B and C. (ii) Calculate molecular mass of C. (i i) What happens when a pinch of sodium carbonate is added to compound B ? Write chemical equation for the reaction. (iv) Draw electron dot structure of compound B. 5 OR (b) (i) What is a homologous series of carbon compounds ? Write the namne and formula of three successive members of the homologous series of compounds having functional group -COOH. (i) Write the name of two carbon compounds in which carbon atoms are arranged in the form of a ring. Draw the structure of any one of the two. 36. Ja) (i) 5 Write the functions of the following parts of human female reproductive system: () Ovary (II) Fallopian tube (III) Uterus State briefly two contraceptive methods used by human males. 5 OR *3/1/2* 21 [P.T.0.] (b) (i) (ii) Differentiate between self-pollination and cross-pollination. ldentify A, B and C in the diagram given below and write one function of each. 5 A B SECTION E The following questions are Source-based/ Case-based questions. Read the case carefully and answer the questions that follow. 37. In our homes, we receive the supply of electric power through a main supply also called mains, either supported through overhead electric poles or by underground cables. In our country the potential difference between the twowires (live wire and neutral wire) of this supply is 220 V. (a) *311/2* Write the colours of the insulation covers of the line wires through which supply comes to our homes. 23 |P.T.0.) (b) What should be the current, rating of the electric circuit (220 V) so that an electric iron of 1 kW power rating can be operated ? (c) (i) 1 What is the function of the earth wire ? State the advantage of the earth wire in domestic electric appliances such as electric iron. 2 OR List two precautions to be taken toavoid electrical accidents. State how these precautions prevent possible damage to the circuit/appliance. 38. 2 The maintenance functions of all living organisms must go on even when they are not doing anything particular. Even when we are just sitting in a class or even asleep, this maintenance job has to go on. These processes require energy to prevent damage and break-down of cells and tissues, which is obtained by the individual maintenance organism from the food prepared by the autotrophs, called producers. Name and define the process by which green plants prepare food. Write chemical equation involved in the above process. (i) State in proper sequence the events that occur in synthesis 2 of food by desert plants. OR (c) (ii) which Explain giving reasons what happens to the rate at food the green plants will prepare during cloudy weather, and () dust. when stomata get blocked due to 2 (II) *31/1/2* 25 [P.T.0.] 39. Seawater contains many salts dissolved in it. Common salt is separated from these salts. Deposits of solid salt are also found in several parts of the world. These large crystals are often brown due to impurities. This is called rock salt and is mined like coal. The common salt is an important raw material for chemicals of daily use. (a) Write balanced chemical equations to show the products formed during electrolysis of brine. (b) 1 List two uses of any one product obtained during electrolysis of brine. (c) (i) 1 A mild non-corrosive basic salt 'A, used for faster cooking, is strongly heated to produce a compound B', that is used for removing permanent hardness of water. Identify A and B and also write the equation for the reaction that occurs when A is heated. 2 OR (c) (ii) Define water of crystallisation. Give two examples of salts that have water of crystallisation. *3/1/2* 27 2

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