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Wednesday, 20 May 2026
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Chemistry Past Questions and Answers

Jamb 1988 Chemistry Questions

Question 11:
A mixture of starch solution and potassium iodide was placed in a test tube. On adding dilute tetraoxosulphate (lV) acid and then K2Cr2O7 solutions, a blue-black colour was produced. In this reaction, the?
  • A Iodide is oxidized
  • B Tetraoxosulphate (Vl) acid acts as an oxidizing agent
  • C Starch has been oxidized
  • D K<sub style='font-size: smaller;'>2</sub>Cr<sub style='font-size: smaller;'>2</sub>O<sub style='font-size: smaller;'>7</sub> is oxidized
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Question 12:
Which of the following will produce the greatest increase in the rate of the chemical reaction represented by the equation Na2S2O3(aq) + 2HCl(aq) → 2NaCI(aq) + H2O(I) + SO2(g) + S(g)?
  • A A decrease in temperature and an increase in the concentration of the reactants
  • B An increase in the temperature and a decrease in the cocentration of the reactants
  • C An increase in temperature and an increase in the concentration of the reactants
  • D A decrease in the temperature and a decrease in the concentration of the reactants
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Question 13:
Which of the followingstatements is TRUE?
  • A The dissolution of NaOH<sub style='font-size: smaller;'>(s)</sub> in water is endothermic
  • B The heat os solution of NaOH<sub style='font-size: smaller;'>(s)</sub> is positive
  • C The NaOH<sub style='font-size: smaller;'>(s)</sub> gains heat from the surroundings
  • D The heat of solution of NaOH<sub style='font-size: smaller;'>(s)</sub> is negative
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Question 14:
Which property of a reversible reaction is affected by a catalyst?
  • A Heat content (enthalphy)
  • B Energy of activation
  • C Free energy change
  • D Equilibrium position
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Question 15:
Which of the following is used in fire extinguishers?
  • A Carbon (ll) oxide
  • B Carbon (lV) oxide
  • C Sulphur (lV) oxide
  • D Ammonia
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