Tiêu đề 1 Chemical reactions and equations - MCQs.pdf ✅

© www.bankofbiology.com 8921 510 476 3 Answer: (b) Sublimation of dry ice 29. Barium hydroxide is added to hydrochloric acid to form a white-coloured barium chloride. Which of the following gives the balanced chemical equation? (a) HCl + Ba(OH)2 → BaCl2 + 2HOH (b) 2HCl + Ba(OH)2 → BaCl2 + 2HOH (c) 2HCl + Ba(OH)2 → BaH2 + 2HCl + O2 (d) HCl + 2Ba(OH) → 2BaCl2 + 2HOH + O2 Answer: (b) 2HCl + Ba(OH)2 → BaCl2 + 2HOH 30. What type of chemical reactions take place when electricity is passed through water? (a) Displacement (b) Combination (c) Decomposition (d) Double displacement Answer: (c) Decomposition 31. In the double displacement reaction between aqueous potassium iodide and aqueous lead nitrate, a yellow precipitate of lead iodide is formed. While performing the activity if lead nitrate is not available, which of the following can be used in place of lead nitrate? (a) Lead sulphate (b) Lead acetate (c) Ammonium nitrate (d) Potassium sulphate Answer: (b) Lead acetate 32. Select the oxidising agent for the following reaction: H2S + I2 → 2HI + S (a) I2 (b) H2S (C) HI (d) S Answer: (a) I2 33. The condition due to aerial oxidation of fats and oils in foods marked by unpleasant smell and taste is called (a) antioxidation (b) reduction (c) rancidity (d) corrosion Answer: (c) rancidity 34. A substance added to food containing fats and oils is (a) Oxidant (b) Rancid (c) Coolant (d) Antioxidant Answer: (d) Antioxidant 35. Electrolysis of water is a decomposition reaction. The mole ratio of hydrogen and oxygen gases liberated during electrolysis of water is: (a) 1:1 (b) 2:1 (c) 4:1 (d) 1:2 Answer: (b) 2:1 36. When SO2 gas is passed through saturated solution of H2S, which of the following reaction occurs? (a) SO2 + 2H2S → 2H2O + 3S (b) SO2 + 2H2S → H2O + 3S (c) SO2 + H2S → H2O + S (d) SO2 + H2O → SO3 + H2 Answer: (a) SO2 + 2H2S → 2H2O + 3S 37. Reactions in which energy is given out are known as: (a) Exothermic (b) Endothermic (c) Combustion (d) Decomposition Answer: (a) Exothermic 38. Name the products formed when iron filings are heated with dilute hydrochloric acid. (a) Fe (III) chloride and water (b) Fe (II) chloride and water (c) Fe (II) chloride and hydrogen gas (d) Fe (III) chloride and hydrogen gas Answer: (c) Fe (II) chloride and hydrogen gas 39. Pb + CuCl2 → PbCl2 + Cu The above reaction is an example of: (a) combination (b) double displacement (c) decomposition (d) displacement Answer: (d) displacement 40. Reaction in which an element displaces another element from its compound is called (a) Substitution (b) Combustion (c) Displacement (d) Decomposition Answer: (c) Displacement 41. A dilute ferrous sulphate solution was gradually added to the beaker containing acidified permanganate solution. The light purple colour of the solution fades and finally disappears. Which is the correct explanation for the observation? (a) KMnO4 is an oxidising agent, it oxidises FeSO4. (b) FeSO4 acts as an oxidising agent and oxidises KMNO4. (c) The colour disappears due to dilution; no reaction is involved. (d) KMnO4 is an unstable compound and decomposes in presence of FeSO4. to a colourless compound. Answer: (a) KMnO4 is an oxidising agent, it oxidises FeSO4 42. Which of the following gases can be used for storage? (a) CO2 or Oxygen (b) Nitrogen or Oxygen (c) CO2 or Helium (d) Helium or Nitrogen Answer: (d) Helium or Nitrogen 43. Chemical equations, the abbreviations represent the correct states of the reactants and products involved at reaction temperature? (a) 2H2 (l) + O2 (l) → 2H2O(g) (b) 2H2 (g) + O2 (l) → 2H2O (l) (c) 2H2 (g) + O2 (g) → 2H2O (l) (d) 2H2 (g) +O2 (g) → 2H2O (g) Answer: (d) 2H2 (g) +O2 (g) → 2H2O (g)