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Wednesday, 20 May 2026
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Chemistry Past Questions and Answers

Chemistry Questions

Question 541:
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 542:
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 543:
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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Question 544:
When H<sub style='font-size: smaller;'>2</sub>S gas is passed into a solution of iron (III) chloride, the colour changes from yellow to green. This is because?
  • A H<sub style='font-size: smaller;'>(s)</sub>S is reduced to S
  • B Fe<sup style='font-size: smaller;'>3+</sup> ions are oxidized by H<sub style='font-size: smaller;'>(s)</sub>S
  • C Fe<sup style='font-size: smaller;'>3+</sup> ions are oxidized Fe<sup style='font-size: smaller;'>3+</sup> ions
  • D Fe<sup style='font-size: smaller;'>3+</sup> ions are reduced to Fe<sup style='font-size: smaller;'>2+</sup> ions
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Question 545:
Suitable reagents for the laboratory preparation nitrogen are?
  • A Sodium dioxonitrate (III) and ammonium chloride
  • B Sodium dioxonitrate (V) and ammonium chloride
  • C Sodium chloride and ammonium chloride
  • D Sodium chloride and ammonium diozonitrate (III)
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