CBSE Class X Important Questions Science Chemistry 2009 2012

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One marks each

Q. 1. What is the basis of Mendeleev’s periodic law?

Q. 2. How many elements are there in a third period?

Q. 3. Sodium and potassium show similar reactivity towards water. What property do these elements possess in common?

Q. 4. Which of the elements F, Cl, Br, I is most reactive?

Q. 5. What are electropositive elements?

Q. 6. Name the bond formed in C2H4.

Q. 7. Why the melting point of metals is high?

Q. 8. Why the noble gases are stable.

Q. 9. Why does CCl4 not conduct electricity?

Q. 10. Give an example of a molecule with double and triple bond.

Q. 11. NaCl is soluble in water but CCl4 is not why?

Q. 12. What happens when lime water reacts with CO2? Write the complete reaction.

Q. 13. Give an example of redox reaction.

Q. 14. What happens when baking soda is heated strongly?

Q. 15. Is copper more reactive than iron? Give reaction in support of your answer.

Q. 16. Name one strong acid and strong base.

Q. 17. Why acetic acid is a weak acid?

Q. 18. Name the acid used in lead storage batteries.

Q. 19. What is the nature of the solution of NaCl in water?

Q. 20. Name the gas whose aqeous solution is basic.

Q. 21. What happens when hydrochloric acid reacts with caustic soda?

Q. 22. What happens when hydrochloric acid reacts with calcium carbonate?

Q. 23. Sulphides ores are generally concentrated by which method.

Q. 24. What is the nature of oxides of metals?

Q. 25. Define minerals and ores.

Q. 26. What is the most common property of metals lying at the bottom of the reactivity series.

Q. 27. What happens when CO2 gas passed into water saturated with ammonia.

Q. 28. Define galvanization.

Q. 29. Name the oxide ore of aluminium.

Q. 30. Which two major constituents of duralium?

Q. 31. What is aqua regia. What is the property of this liquid.

Q. 32. Name the constituents of Brass and Bronze. What is their use?

Q. 33. What are the two things necessary for rusting?

Q. 34. Give the molecular formula of washing soda.

Q. 35. What is the general formula of alcohols ?

Q. 36. What is fermentation ?

Q. 37. Write the reaction of hydration of ethene.

Q. 38. Write the equation for the combustion of ethanol.

Q. 39. What is obtained when ethanol reacts with sodium metal?

Q. 40. What is esterification?

Q. 41. Write the chemical equation of oxidation of methanol to methanal.

Q. 42. Write the equation showing reaction between acetic acid and sodium metal.

Q. 43. Give the example of the neutralisation reaction of acetic acid.

Q. 44. What is sodalime ?

Q. 45. What is decarboxylation reaction?

Q. 46. What is saponification ?

Q. 47. What is soap ?

Q. 48. Write the equation of the reaction of reduction of methanal.

Q. 49. How can you convert propanone to ethanoic acid?

Q. 50. What is the colour of acetic acid.

Q. 51. When a piece of zinc is added to blue copper sulphate solution, the colour of the solution is?

Q. 52. When a piece of iron is added to blue copper sulphate solution, the colour of the solution is?

Q. 53. Which organic compound is formed when acetic acid is warmed with ethyl alchohol in the presence of concentrated H2SO4?

Q. 54. Give the IUPAC name of formic acid.

Q. 55. What is the smell of acetic acid?

Q. 56. What is universal indicator.

Q. 57. Name three indicators which are commonly used in a laboratory.

Q. 58. What will be the effect on a blue litmus paper when it is brought in contact with SO2 dissolved in water.

Q. 59. Fe2O3 + 2Al → Al2O3 +2Fe. This reaction is an example of which reaction.

Q. 61. Hydrogen gas combines with nitrogen.

1. Hydrogen sulphide gas burns in air.
2. Barium chloride reacts with aluminium sulphate.
3. Potassium metal reacts with water
4. Calcium hydroxide + CO2
5. Zinc + Silver nitrate
6. Aluminium + Copper chloride
7. Barium chloride reacts with Potassium sulphate.
8. Potassium bromide + Barium iodide
9. Zinc carbonate (heat)
10. Hydrogen + Chlorine
11. Magnesium + HCl
12. Plaster of paris is treated with water

Q. 62. What is corrosion and rancidity?

Q. 63. Why should curd and sour substances not keep in brass and copper vessels?

Q. 64. Why does dry HCl gas not change the colour of dry litmus paper.

Q. 65. While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid.

Q. 66. Do basic solutions also have H­+ ions? If yes, then why are these basic?

Q. 67. Name the substance which on treating with chlorine yields bleaching powder. Give reaction also.

Q. 68. Name the sodium compound which is used for softening hard water.

Q. 69. Why does distilled water not conduct electricity, whereas rain water does?

Q. 70. Why do acids do not show acidic behaviour in the absence of water?

Q. 71. Plaster of paris should be stored in a moistened-proof container. Explain why?

Q. 72. Give two important uses of washing soda and baking soda.

Q. 73. Milkman adds a very small amount of baking soda to freash milk.

1. Why does he shift the pH of the fresh milk from 6 to slightly alkaline?
2. Why does this milk take a long time to set as curd?

Q. 74. .Why is sodium kept immersed in kerosene oil?

Q. 75. Write equation for the reaction of

1. iron with steam
2. Calcium and potassium with water.

Q. 76. What would you observe when zinc is added to a solution of iron sulphate? Write the chemical reaction that takes place.

Q. 77. What chemical process is used for obtaining a metal from its oxide?

Q. 78. Food cans coated with tins and not with zinc why?

Q. 79. What are amphoteric oxides? Give two examples.

Q. 80. State two ways to prevent rusting of iron.

Q. 81. Aluminium is a highly reactive metal, yet it is used to make utensils for cooking. Why?

Q. 82. What are the two properties of carbon which lead to the huge number of carbon compounds we see around us?

Q. 83. Would you be able to check if water is hard by using a detergent?

Q. 84. What is hydrogenation? What is its industrial application?

Q. 85. Why do you think the noble gases are placed in a separate group?

Each two marks:

Q.1. Why should magnesium ribbon be cleaned before burning in air?

Q.2. What is a balanced chemical equation? Why should chemical equation be balaced?

Q.3. What does one mean by exothermic and endothermic reactions? Give examples.Oil and fat containing food items are flushed with nitrogen. Why?

Q.4. Why do HCl, HNO3 etc. show acidic character in aqeous solution while solutions of compounds like alchohol and glucose do not show acidic character?

Q.5. Show the formation of Na2O and MgO by the transfer of electrons.

Q.6. In the electrolytic refining of a metal M, What would you take as anode, the cathode and the electrolyte?

Q.7. Why sour substances are effective in cleaning the tarnished copper vessels?

Q.8. Draw the structure of the following compounds.

1. Ethanoic acid
2. Bromopentane
3. iii. Butan
one
4. Hexanal

Q.9. . How would you distinguish experimently between an alcohol and a carboxylic acid?

Q.10. Why is agitation necessary to get clean clothes?

Q.11. Why does micelle formation take place when soap is added to water? Will a micelle be formed in other solvents such as ethanol also?

Q.12. Explain the formation of scum when hard water is treated with soap.

Q.13. Give a test that can be used to differentiate chemically between butter and cooking oil.

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  • Ques->what happened on complete combustion of ethanol?
    PLESE SOMEONE ANSWER ME FAST I’LL BE KIND TO U

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  • Q. 63. Why should curd and sour substances not keep in brass and copper vessels?

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  • most imporant questions that can come in my 10th board. sir please

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  • EXPLAIN WHY SOLID COPPER SULPHATE DOES NOT CONDUCT ELECTRICITY BUT AN AQUEOUS SOLUTION OF COPPER SULPHATE CONDUCT

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  • Why should curd and sour substances not be kept in brass and copper vessels ?

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  • Q. 1. What is the basis of Mendeleev’s periodic law?

    Q. 2. How many elements are there in a third period?

    Q. 3. Sodium and potassium show similar reactivity towards water. What property do these elements possess in common?

    Q. 4. Which of the elements F, Cl, Br, I is most reactive?

    Q. 5. What are electropositive elements?

    Q. 6. Name the bond formed in C2H4.

    Q. 7. Why the melting point of metals is high?

    Q. 8. Why the noble gases are stable.

    Q. 9. Why does CCl4 not conduct electricity?

    Q. 10. Give an example of a molecule with double and triple bond.

    Q. 11. NaCl is soluble in water but CCl4 is not why?

    Q. 12. What happens when lime water reacts with CO2? Write the complete reaction.

    Q. 13. Give an example of redox reaction.

    Q. 14. What happens when baking soda is heated strongly?

    Q. 15. Is copper more reactive than iron? Give reaction in support of your answer.

    Q. 16. Name one strong acid and strong base.

    Q. 17. Why acetic acid is a weak acid?

    Q. 18. Name the acid used in lead storage batteries.

    Q. 19. What is the nature of the solution of NaCl in water?

    Q. 20. Name the gas whose aqeous solution is basic.

    Q. 21. What happens when hydrochloric acid reacts with caustic soda?

    Q. 22. What happens when hydrochloric acid reacts with calcium carbonate?

    Q. 23. Sulphides ores are generally concentrated by which method.

    Q. 24. What is the nature of oxides of metals?

    Q. 25. Define minerals and ores.

    Q. 26. What is the most common property of metals lying at the bottom of the reactivity series.

    Q. 27. What happens when CO2 gas passed into water saturated with ammonia.

    Q. 28. Define galvanization.

    Q. 29. Name the oxide ore of aluminium.

    Q. 30. Which two major constituents of duralium?

    Q. 31. What is aqua regia. What is the property of this liquid.

    Q. 32. Name the constituents of Brass and Bronze. What is their use?

    Q. 33. What are the two things necessary for rusting?

    Q. 34. Give the molecular formula of washing soda.

    Q. 35. What is the general formula of alcohols ?

    Q. 36. What is fermentation ?

    Q. 37. Write the reaction of hydration of ethene.

    Q. 38. Write the equation for the combustion of ethanol.

    Q. 39. What is obtained when ethanol reacts with sodium metal?

    Q. 40. What is esterification?

    Q. 41. Write the chemical equation of oxidation of methanol to methanal.

    Q. 42. Write the equation showing reaction between acetic acid and sodium metal.

    Q. 43. Give the example of the neutralisation reaction of acetic acid.

    Q. 44. What is sodalime ?

    Q. 45. What is decarboxylation reaction?

    Q. 46. What is saponification ?

    Q. 47. What is soap ?

    Q. 48. Write the equation of the reaction of reduction of methanal.

    Q. 49. How can you convert propanone to ethanoic acid?

    Q. 50. What is the colour of acetic acid.

    Q. 51. When a piece of zinc is added to blue copper sulphate solution, the colour of the solution is?

    Q. 52. When a piece of iron is added to blue copper sulphate solution, the colour of the solution is?

    Q. 53. Which organic compound is formed when acetic acid is warmed with ethyl alchohol in the presence of concentrated H2SO4?

    Q. 54. Give the IUPAC name of formic acid.

    Q. 55. What is the smell of acetic acid?

    Q. 56. What is universal indicator.

    Q. 57. Name three indicators which are commonly used in a laboratory.

    Q. 58. What will be the effect on a blue litmus paper when it is brought in contact with SO2 dissolved in water.

    Q. 59. Fe2O3 + 2Al → Al2O3 +2Fe. This reaction is an example of which reaction.

    Q. 61. Hydrogen gas combines with nitrogen.

    1. Hydrogen sulphide gas burns in air.
    2. Barium chloride reacts with aluminium sulphate.
    3. Potassium metal reacts with water
    4. Calcium hydroxide + CO2
    5. Zinc + Silver nitrate
    6. Aluminium + Copper chloride
    7. Barium chloride reacts with Potassium sulphate.
    8. Potassium bromide + Barium iodide
    9. Zinc carbonate (heat)
    10. Hydrogen + Chlorine
    11. Magnesium + HCl
    12. Plaster of paris is treated with water

    Q. 62. What is corrosion and rancidity?

    Q. 63. Why should curd and sour substances not keep in brass and copper vessels?

    Q. 64. Why does dry HCl gas not change the colour of dry litmus paper.

    Q. 65. While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid.

    Q. 66. Do basic solutions also have H­+ ions? If yes, then why are these basic?

    Q. 67. Name the substance which on treating with chlorine yields bleaching powder. Give reaction also.

    Q. 68. Name the sodium compound which is used for softening hard water.

    Q. 69. Why does distilled water not conduct electricity, whereas rain water does?

    Q. 70. Why do acids do not show acidic behaviour in the absence of water?

    Q. 71. Plaster of paris should be stored in a moistened-proof container. Explain why?

    Q. 72. Give two important uses of washing soda and baking soda.

    Q. 73. Milkman adds a very small amount of baking soda to freash milk.

    1. Why does he shift the pH of the fresh milk from 6 to slightly alkaline?
    2. Why does this milk take a long time to set as curd?

    Q. 74. .Why is sodium kept immersed in kerosene oil?

    Q. 75. Write equation for the reaction of

    1. iron with steam
    2. Calcium and potassium with water.

    Q. 76. What would you observe when zinc is added to a solution of iron sulphate? Write the chemical reaction that takes place.

    Q. 77. What chemical process is used for obtaining a metal from its oxide?

    Q. 78. Food cans coated with tins and not with zinc why?

    Q. 79. What are amphoteric oxides? Give two examples.

    Q. 80. State two ways to prevent rusting of iron.

    Q. 81. Aluminium is a highly reactive metal, yet it is used to make utensils for cooking. Why?

    Q. 82. What are the two properties of carbon which lead to the huge number of carbon compounds we see around us?

    Q. 83. Would you be able to check if water is hard by using a detergent?

    Q. 84. What is hydrogenation? What is its industrial application?

    Q. 85. Why do you think the noble gases are placed in a separate group?

    jay patil on 15 Jun 2011
  • What is the basis of Mendeleev’s periodic law?
    Give a test that can be used to differentiate chemically between butter and cooking oil.

    jay patil on 15 Jun 2011
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    2.bronmopentane
    3. iii butan
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