Science Sample Paper-3
Question 1. What is glacial acetic acid? What is its melting point?
Question 2. Name the two elements which are present both in CNG and petroleum.
Question 3. Translate the following statements into balanced chemical equations: (a) Sodium metal reacts with water to give sodium hydroxide and hydrogen gas. (b) Ammonium chloride solution is added to barium hydroxide solution to give ammonium hydroxide and barium chloride.
Question 4. How is aluminum used to join railway tracks?
Question 5. If the image formed by a lens for all positions of an object placed in front of it is always erect and diminished, what is the nature of this lens? Draw a ray diagram to justify your answer.
Question 6. Write the chemical name of baking soda. Write balanced chemical equation for its preparation. Mention its one use. Or State reason for the following: (a) A tarnished copper vessel begins to shine again when rubbed with lemon. (b) All alkalis are bases but all bases are not alkalis.
(c) Use of a mild base like baking soda on the honey- bee stung area gives relief.
Question 7. Na, Mg and Al are the elements of the 3rd period of the Modern Periodic Table having group number 1, 2 and 13 respectively. Which one of these elements has the (a) highest valency, (b) largest atomic radius, and (c) maximum chemical reactivity? Justify your answer stating the reason for each. Question 8. (a) Name the following: (i) The three carbon molecule that is formed due to break- down of glucose during respiration. (ii) The nitrogenous waste that is removed from the blood in our kidneys (b) How do unicellular organisms generally remove waste?
Question 9. Explain how the movement of leaves of a sensitive plant different from movement of shoots towards light?
Question 10. With the help of one example for each, distinguish between the acquired traits and the inherited traits. Why are the traits/experiences acquired during the entire lifetime on an individual not inherited in the next generation?
Question 11. A student suffering from myopia is not able to see distinctly the objects placed beyond 5 m. List two possible reasons due to which this defect of vision may have arisen. With the help of ray diagrams, explain, (a) Why the student is unable to see distinctly the objects placed beyond 5 m from his eyes. (b) The type of the corrective lens used to restore proper vision and how this defect is corrected by the use of this lens. Or Draw a labelled diagram of the human eye; showing ciliary muscles, eye lens, cornea, retina and blind spot.
Question 12. Kritika observed that the tube lights in the corridor of her school were always switched on the whole day. She brought the matter to the notice of her class teacher who talked to the Principal about it. The Principal took immediate action. (a) Kritika helped in a way to reduce air pollution. Explain how. (b) Kritika was appreciated by the teachers and the Principal for portraying which values? (c) How can the consumption of electricity be reduced in a school?
Question 13. (a) Magnetic field lines of two bar magnets A and B are as shown below. Name the poles of the magnets facing each other.
(b) How does he strength of the magnetic field at the centre of a current carrying circular coil depend on the (i) Radius of the oil, (ii) Number of turns in the oil, and (iii) Strength of the current flowing in the coil?
Question 14. List any three advantages of using solar cooker for cooking instead of fossil fuels.
Question 15. (a) State one advantage of conserving (i), forests, and (ii) wildlife. (b) Explain two main advantages associated with water harvesting at the community level.
Question 16. (a) A dry pallet of common base 'X', when kept in open air absorbs moisture and turns sticky. The compound is also a by- product of chlor- alkali process. Identify 'X'. What type of reaction occurs when 'X' is treated with strong acid? Write a balanced chemical equation for such reaction. (b) Can we store the base 'X' in an aluminum container? Give reason in support of your answer.
Question 17. (a) Write the structural formula of ethanol. What happens when it is heated with excess of conc. đ??ť2 đ?‘†đ?‘‚4 đ?‘Žđ?‘Ą 443 đ??ž? Write the chemical equation for the reaction stating the role of conc. đ??ť2 đ?‘†đ?‘‚4 in this reaction. (b) Distinguish between Esterification and Saponification reactions with the help of the chemical equations for each. State one use of each (i) esters, and (ii) saponification process.
Question 18. (a) Draw the structure of a nephron and label the following parts on it: (i) Renal artery
(ii) Bowman's capsule
(iv) Collecting duct.
(b) State the function of Bowman's capsule and glomerulus.
Question 19. . (a) Reproduction is one of the most important characteristics of living beings. Give two reasons in support of the statement. (b) List three techniques that have been developed to prevent pregnancy. Which one of these techniques is not meant for males? How does the use of these techniques have a direct impact on the health and prosperity of a family? Or List four points of significance of reproductive health in a society. Name any two areas related to reproductive health which have improved over the past 50 years in our country.
Question 20. (a) If the image formed by mirror for all positions of the object placed in front of it is always diminished, erect and virtual, state the type of the mirror and also draw a ray diagram to justify your answer. Write one use such mirrors are put to and why. (b) Define the radius of curvature of spherical mirrors. Find the nature and focal length of a spherical mirror whose radius of curvature is + 24 cm.
Question 21. (a) Can you run an electric geyser with power rating 2 kW; 220V on a 5 A line? Give reason to justify your answer. (b) What will happen to the heat produced if the current passing through an electric heater has been halved?
SECTION- B Question 22. While performing an experiment, a student observes that when he heats some green crystals in a boiling tube, the colour of the crystals changes to brown and a gas evolves which smells like burning sulphur. Interpret the observations and results.
Question 23. A student is studying the properties of acetic acid in the his school laboratory. List two physical and two chemical properties which he must observe and note in his record book.
Question 24. Find the staining and mounting materials when a leaf epidermal peel looks pinkish red when observed under a microscope.
Question 25. An ammeter has a range of 0- 3 ampere and there are 30 divisions on its scale. Calculate the least count of the ammeter.
26. To find the image distance for varying object distances in case of a convex lens of focal length 15 cm, a student obtains on a screen a sharp image of a bright object by placing it at
20 cm distance from the lens. After that he gradually moves the object away from the lens and each time focuses the image on the screen. (a) In which direction- towards or away from the lens does he move the screen to focus the object? (b) How does the size of image change? (c) Approximately at what distance does he obtain the image of magnification âˆ’1? (d) How does the intensity of image change as the object moves farther and farther away from the lens?
Question 27. In which asexual reproduction two individuals are formed from a single parent and the parental identity is lost? Draw the initial and the final stages of this type of reproduction to justify your answer. Write the event with which this process starts.
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Published on Mar 14, 2018