Class 10 Science Chapter 1 Chemical Reactions and Equations

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Class 10 Science Chapter 1 Chemical Reactions and Equations

Question: A reaction in which two or more substances combine to form a single product is called a ………. reaction.
Answer: Combination

Question: The chemical formula of quicklime is ……….
Answer: CaO

Question: In a displacement reaction, a more reactive metal displaces a ………. reactive metal from its compound.
Answer: Less

Question: The balanced chemical equation for the reaction between zinc and dilute sulphuric acid is ……….
Answer: Zn + H₂SO₄ → ZnSO₄ + H₂

Question: When magnesium ribbon burns in oxygen, it forms ……….
Answer: Magnesium oxide

Question: In the reaction 2H2+O2→2H2O2H₂ + O₂ → 2H₂O, the product formed is ……….
Answer: Water

Question: A decomposition reaction where energy is absorbed from light is called ………. decomposition.
Answer: Photochemical

Question: When lead nitrate is heated, it decomposes to form ………., ………., and oxygen.
Answer: Lead oxide, nitrogen dioxide

Question: The gas collected at the cathode during the electrolysis of water is ……….
Answer: Hydrogen

Question: When iron reacts with copper sulphate, the product formed is ………. and copper.
Answer: Iron sulphate

Question: The reaction 3Fe+4H2O→Fe3O4+4H23Fe + 4H₂O → Fe₃O₄ + 4H₂ is an example of a ………. reaction.
Answer: Combination

Question: The process in which fats and oils are oxidized to produce a foul smell is called ……….
Answer: Rancidity

Question: In the refining of silver, copper displaces silver from ………. solution.
Answer: Silver nitrate

Question: The chemical name of the white precipitate formed when barium chloride reacts with sodium sulphate is ……….
Answer: Barium sulphate

Question: The reaction CaO+H2O→Ca(OH)2+HeatCaO + H₂O → Ca(OH)₂ + Heat is an example of an ………. reaction.
Answer: Exothermic

Question: A solution used for whitewashing walls is ……….
Answer: Calcium hydroxide

Question: In the reaction Zn+CuSO4→ZnSO4+CuZn + CuSO₄ → ZnSO₄ + Cu, the more reactive metal is ……….
Answer: Zinc

Question: A chemical equation must always be ………. to follow the law of conservation of mass.
Answer: Balanced

Question: The chemical formula of slaked lime is ……….
Answer: Ca(OH)₂

Question: The green coating formed on copper articles over time is due to the formation of ……….
Answer: Basic copper carbonate

Question: The brown fumes evolved when lead nitrate is heated are of ………. gas.
Answer: Nitrogen dioxide

Question: The reaction NaOH+HCl→NaCl+H2ONaOH + HCl → NaCl + H₂O is an example of a ………. reaction.
Answer: Neutralization

Question: The black coating formed on silver articles is due to the formation of ……….
Answer: Silver sulphide

Question: The reddish-brown coating formed on iron articles over time is called ……….
Answer: Rusting

Question: The symbol (g) in a chemical equation indicates that the substance is in the ………. state.
Answer: Gaseous

Question: The gas evolved when acids react with metals is ……….
Answer: Hydrogen

Question: A reaction that involves both oxidation and reduction is called a ………. reaction.
Answer: Redox

Question: In the reaction 2AgCl→2Ag+Cl22AgCl → 2Ag + Cl₂, the substance undergoing decomposition is ……….
Answer: Silver chloride

Question: The chemical name of the product formed when calcium hydroxide reacts with carbon dioxide is ……….
Answer: Calcium carbonate

Question: A reaction that produces energy in the form of heat is called an ………. reaction.
Answer: Exothermic

Fill in the blanks

  1. A reaction in which two or more substances combine to form a single product is called a ______ reaction.
  2. The chemical formula of quicklime is ______.
  3. In a displacement reaction, a more reactive metal displaces a ______ reactive metal from its compound.
  4. The balanced chemical equation for the reaction between zinc and dilute sulphuric acid is ______.
  5. When magnesium ribbon burns in oxygen, it forms ______.
  6. In the reaction 2H2(g)+O2(g)→2H2O(l)2H_2(g) + O_2(g) \rightarrow 2H_2O(l), the product formed is ______.
  7. A decomposition reaction where energy is absorbed from light is called ______ decomposition.
  8. When lead nitrate is heated, it decomposes to form ______, ______, and oxygen.
  9. The gas collected at the cathode during the electrolysis of water is ______.
  10. When iron reacts with copper sulphate, the product formed is ______ and copper.
  11. The reaction 3Fe+4H2O→Fe3O4+4H23Fe + 4H_2O \rightarrow Fe_3O_4 + 4H_2 is an example of ______ reaction.
  12. The process in which fats and oils are oxidized to produce a foul smell is called ______.
  13. In the refining of silver, copper displaces silver from ______ solution.
  14. The chemical name of the white precipitate formed when barium chloride reacts with sodium sulphate is ______.
  15. The reaction CaO(s)+H2O(l)→Ca(OH)2(aq)+HeatCaO(s) + H_2O(l) \rightarrow Ca(OH)_2(aq) + Heat is an example of an ______ reaction.
  16. A solution used for whitewashing walls is ______.
  17. In the reaction Zn+CuSO4→ZnSO4+CuZn + CuSO_4 \rightarrow ZnSO_4 + Cu, the more reactive metal is ______.
  18. A chemical equation must always be ______ to follow the law of conservation of mass.
  19. The chemical formula of slaked lime is ______.
  20. The green coating formed on copper articles over time is due to the formation of ______.
  21. The brown fumes evolved when lead nitrate is heated are of ______ gas.
  22. The reaction NaOH(aq)+HCl(aq)→NaCl(aq)+H2O(l)NaOH(aq) + HCl(aq) \rightarrow NaCl(aq) + H_2O(l) is an example of a ______ reaction.
  23. The black coating formed on silver articles is due to the formation of ______.
  24. The reddish-brown coating formed on iron articles over time is called ______.
  25. The symbol (g) in a chemical equation indicates that the substance is in the ______ state.
  26. The gas evolved when acids react with metals is ______.
  27. A reaction that involves both oxidation and reduction is called a ______ reaction.
  28. In the reaction 2AgCl(s)→Sunlight2Ag(s)+Cl2(g)2AgCl(s) \xrightarrow{\text{Sunlight}} 2Ag(s) + Cl_2(g), the substance undergoing decomposition is ______.
  29. The chemical name of the product formed when calcium hydroxide reacts with carbon dioxide is ______.
  30. A reaction that produces energy in the form of heat is called an ______ reaction.
  31. The representation of a chemical reaction using symbols and formulas is called a ______.
  32. The reaction C(s)+O2(g)→CO2(g)C(s) + O_2(g) \rightarrow CO_2(g) is an example of a ______ reaction.
  33. In the reaction 2KBr(aq)+BaI2(aq)→2KI(aq)+BaBr2(s)2KBr(aq) + BaI_2(aq) \rightarrow 2KI(aq) + BaBr_2(s), the precipitate formed is ______.
  34. The reaction in which a compound breaks down into two or more simpler substances is called a ______ reaction.
  35. A redox reaction involves the simultaneous occurrence of ______ and ______.
  36. When food gets oxidized, the process is called ______.
  37. The compound responsible for the blackening of silver articles is ______.
  38. In the reaction H2S(g)+Cl2(g)→S(s)+2HCl(g)H_2S(g) + Cl_2(g) \rightarrow S(s) + 2HCl(g), the substance being oxidized is ______.
  39. When hydrochloric acid reacts with sodium hydroxide, the product formed is ______ and ______.
  40. The process of balancing a chemical equation ensures the law of ______.
  41. The process in which iron reacts with oxygen and moisture to form rust is called ______.
  42. During the corrosion of silver, it reacts with sulphur in the air to form ______.
  43. The chemical reaction that takes place during respiration is an example of an ______ reaction.
  44. When calcium carbonate is heated, it decomposes to form ______ and ______.
  45. The chemical formula for rust is ______.
  46. The reaction between zinc and hydrochloric acid produces ______ gas.
  47. The reaction Fe2O3+2Al→Al2O3+2FeFe_2O_3 + 2Al \rightarrow Al_2O_3 + 2Fe is known as a ______ reaction.
  48. The heat evolved during the slaking of lime indicates that it is an ______ reaction.
  49. In the electrolysis of water, the gas evolved at the anode is ______.
  50. A skeletal chemical equation is an unbalanced equation where the number of ______ is not equal on both sides.
  51. The brown color on an iron nail after a displacement reaction is due to the deposition of ______.
  52. The substance that is reduced in the reaction CuO+H2→Cu+H2OCuO + H_2 \rightarrow Cu + H_2O is ______.
  53. During a precipitation reaction, an ______ substance is formed in the solution.
  54. The substance oxidized in the reaction Zn+CuSO4→ZnSO4+CuZn + CuSO_4 \rightarrow ZnSO_4 + Cu is ______.
  55. The physical state of reactants and products in a chemical equation is represented by notations such as ______ for solid and ______ for gas.
  56. The process of burning magnesium in air results in the formation of ______ with a dazzling white flame.
  57. A reaction in which heat is absorbed is called an ______ reaction.
  58. The reaction 6CO2+6H2O→sunlight, chlorophyllC6H12O6+6O26CO_2 + 6H_2O \xrightarrow{\text{sunlight, chlorophyll}} C_6H_{12}O_6 + 6O_2 is an example of a ______ reaction.
  59. The element that gets displaced in a displacement reaction depends on its ______ in the reactivity series.
  60. The reaction Pb(NO3)2→PbO+NO2+O2Pb(NO_3)_2 \rightarrow PbO + NO_2 + O_2 involves the decomposition of lead nitrate into ______ and ______.

Answers:-

  1. Combination
  2. CaO\text{CaO}
  3. Less
  4. Zn + H2SO4→ZnSO4+H2\text{Zn + H}_2\text{SO}_4 \rightarrow \text{ZnSO}_4 + \text{H}_2
  5. Magnesium oxide
  6. Water
  7. Photochemical
  8. Lead oxide, nitrogen dioxide
  9. Hydrogen
  10. Iron sulphate
  11. Combination
  12. Rancidity
  13. Silver nitrate
  14. Barium sulphate
  15. Exothermic
  16. Calcium hydroxide (Ca(OH)2\text{Ca(OH)}_2)
  17. Zinc
  18. Balanced
  19. Ca(OH)2\text{Ca(OH)}_2
  20. Basic copper carbonate
  21. Nitrogen dioxide
  22. Neutralization
  23. Silver sulphide
  24. Rusting
  25. Gaseous
  26. Hydrogen
  27. Redox
  28. Silver chloride
  29. Calcium carbonate
  30. Exothermic
  1. Chemical equation
  2. Combination
  3. Barium bromide
  4. Decomposition
  5. Oxidation, reduction
  6. Rancidity
  7. Silver sulphide
  8. Hydrogen sulphide
  9. Water, sodium chloride
  10. Conservation of mass
  11. Rusting
  12. Silver sulphide
  13. Exothermic
  14. Calcium oxide, carbon dioxide
  15. Fe2O3⋅xH2O\text{Fe}_2\text{O}_3 \cdot x \text{H}_2\text{O}
  16. Hydrogen
  17. Displacement
  18. Exothermic
  19. Oxygen
  20. Atoms
  21. Copper
  22. Copper oxide (CuO\text{CuO})
  23. Insoluble
  24. Zinc
  25. (s), (g)
  26. Magnesium oxide
  27. Endothermic
  28. Combination
  29. Position
  30. Lead oxide, nitrogen dioxide

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