Questions 1 to 4 are one mark questions. These are to be answered in one word or one sentence. Section A
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1. State the chemical change that takes place when lime stone is heated strongly.
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2. .Why do silver articles become black after some time when exposed to air ?
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3. Name the device which directly converts solar energy into electrical energy.
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4. What are amphoteric oxides ? Choose the amphoteric oxides amongst the following oxides. Na2O, ZnO, Al2O3, CO2, H2O
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Questions 5 to 13 are two marks questions. These are to be answered in about 30 words each.
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5. Draw circuit symbols of the following components : (i) Variable resistance or rheostat
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(ii) Plug key or switch (closed)
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6. What are antacids ? Name two compounds which are used as antacids.
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7. A small amount of ferrous sulphate crystals were heated in a hard glass test tube ? (i) Write the equations involved in the above reaction (ii) Name the type of reaction that takes/ place ?
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8. A white salt on heating decomposes to give brown fumes and a residue is left behind. (i) Name the salt. (ii) Write the equation for the decomposition reaction.
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9. Out of two solar cookers one was covered by a plane glass slab and the other was left open. Which of two solar cookers will be more efficient and why ?
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10. A wire of resistance R is cut into three equal parts. (i) Find the value of resistance of each part in terms of the original resistance R ? (ii) If these three pieces are connected in parallel, what is the ratio of the equivalant resistance so obtained with the original resistance ?
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11. How does the strength of the Magnetic field at the centre of a circular coil of a wire depend on : (a) radius of the coil (b) number of turns in the coil
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12. State Ohm’s law and write the condition in which this law is obeyed ?
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13. (a) What happens when quick lime is added to water ? (b) Write chemical equation for the above reaction. (c) Which type of reaction is this?
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Questions 14 to 22 are three marks questions. These are to be answered in about 50 words each
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14. Write balanced equations for the reaction of : (a) iron with steam (b) calcium with water.
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15. Write the chemical name and formula of washing soda. How is it prepared? Write balanced chemical equation of the reaction.
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16. (a) How sodium hydroxide is prepared from sodium chloride ? (b) What will be the pH of the following salts. (i) salt made of strong acid and strong base. (ii) salt made of strong acid and weak base.
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17. Determine the ratio of the (a) highest (b) lowest resistance that can be secured by combining four coils of resistance 4 W, 8 W, 12 W, and 24 W in an electric circuit.
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18. An electric bulb draws a current of 0.8A from 250 V mains. The bulb is used on an average 8 hours a day, If energy costs Rs 3 per kWh, calculate the monthly bill for 30 days.
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19. What is the function of an earth wire ? Why is it to necessary to earth metallic appliances ?
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20. (a) Define ‘water of crystallization’. (b) Give two examples of substances having water of crystallization. Write their molecular formulae also.
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21. What are exothermic and endothermic reactions. Explain with the help of one example each.
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22. In a house, four 60W electric bulbs are lighted for 2 hours and two 100W bulbs are lighted for 4 hours everyday. Calculate the energy consumed in the house for 30 days.
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Questions 23 to 25 are five marks questions. These are to be answered in about 70 words each.
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23. (i) What causes rusting of iron ? Design an activity to show the conditions needed for iron nails to rust. (ii) Why do we paint iron articles ?
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24. (i) Two circular coils P and Q are kept close to each other, of which coil P carries a current. If coil P is moved towards Q, will some current be induced in coil Q ? Give reason for your answer and name the phenomenon involved. (ii) What happens if coil P is moved away from Q ? (iii) State any two methods of inducing current in a coil.
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25. (i) With the help of an activity, explain the method of inducing electric current in a coil with a moving magnet. State the rule used to find the direction of electric current thus generated in the coil. (ii) Two circular coils P and Q are kept close to each other, of which coil P carries a current. What will you observe in Q ? (a) If current in the coil P is changed ?
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Section B
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Questions 26 to 41 in section B are multiple choice questions based on practical skills. Each question is a one mark question. You are to select one most appropriate response out of the four provided to you.
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(b) If both the coils are moved in the same direction with the same speed ? Give reason.
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26.A student tested the pH of distilled water and found that the colour of the pH paper changed to green. He checked the pH again after dissolving a pinch of common salt in it. The colour of the pH paper this time would be :
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(a) Green (b) Yellow (c) Red (d) Blue
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27. Two solutions A and B were found to have pH value of 6 and 8 respectively. The inference which can be drawn is :
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(a) The strength of solution B is higher than that of A. (b) A is an acid while B is base.
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(c) both are acidic solutions. (d) both are basic solutions.
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28. Which of the following chemical properties are shown by dilute hydrochloric acid ? (i) It turns blue litmus red (ii) It turns red litmus blue (iii) It reacts with zinc and a gas is evolved (iv) It reacts with solid sodium carbonate to give brisk effervescence
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(a) (i) and (ii) only (b) (i) and (iii) only
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(c) (i), (iii) and (iv) only (d) (ii), (iii) and (iv) only
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29. While doing an experiment a student observed that the blue colour of the aqueous copper
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sulpate solution was changed to pale green by immersing a metal rod in it. The metal of the rod
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used by the student is : (a) iron (b) zinc (c) silver (b) aluminium
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30. Iron filings were added to a solution of copper sulphate. After 10 minutes, it was observed that the blue colour of the solution has changed and a layer has deposited on iron filings. Which one of the following set of colours correspond to the colour of the solution and the colour of the coating respectively?
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(a) Yellow and green. (b) Brown and blue.
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(c) Red and greenish blue. (d) Light green and reddish brown.
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31. A student connects a circuit to study Ohm’s law using a resistor of 3 ohm and a battery eliminator of 6 V. Which of the ammeter should be chosen to read the value of current for this circuit, if the ammeters available in the laboratory have the following ranges? (a) 0 200 m A (b) 0 - 100 mA (c) 0 - 1 A (d) 0 - 2 A
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32. Rahul adds aqueous solution of barium chloride to an aqueous solution of sodium sulpate. He would observe that
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(a) a pungent smelling gas is evolved. (b) the colour of the solution turns red.
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(c) a yellow precipitate is formed after sometime.
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(d) a white precipitate is formed almost immediately.
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33. The colour of metal deposited when iron nails are dipped in aq. solution of copper sulphate is : (a) reddish brown (b) no metal is deposited (c) grey (d) silvery white
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34. A blue litmus paper was first dipped in dil. HCI and then in dil. NaOH solution. It was observed that the colour of the litmus paper :
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(a) Changed to red (b) Changed first to red and then to blue
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(c) Changed blue to colorless (d) Remained blue in both the solutions
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35. On putting a few drops of a liquid on a pH strip, the colour of the pH strip changed to red. This liquid is most probably :
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(a) NaHCO3 (b) HCl (c) NaOH (d) C2H5OH
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Thanks for the information about the details
ReplyDeletecbse 10th results 2021