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Thursday, 11 June 2026
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Chemistry Past Questions and Answers

Jamb 2003 Chemistry Questions

Question 26:
When at equilibrium, which of the reactions below will shift to the right if the pressure is increased and the temperature is kept constant?
  • A 2SO<sub style='font-size: smaller;'>3(g)</sub> ↔ 2SO<sub style='font-size: smaller;'>2(g)</sub> + O<sub style='font-size: smaller;'>2(g)</sub>
  • B 2CO<sub style='font-size: smaller;'>2(g)</sub> ↔ 2CO<sub style='font-size: smaller;'>(g)</sub> + O<sub style='font-size: smaller;'>2(g)</sub>
  • C 2H<sub style='font-size: smaller;'>2(g)</sub> + O<sub style='font-size: smaller;'>2(g)</sub> ↔ 2H<sub style='font-size: smaller;'>2</sub>O<sub style='font-size: smaller;'>(g)</sub>
  • D 2NO<sub style='font-size: smaller;'>(g)</sub> ↔ N<sub style='font-size: smaller;'>2(g)</sub> + O<sub style='font-size: smaller;'>2(g)</sub>
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Question 27:
In the electrolysis of a concentrated solution of sodium chloride using electrodes, which of the following ions are discharged at the cathode and anode respectively?
  • A Na<sup style='font-size: smaller;'>+</sup> and Cl<sup style='font-size: smaller;'>-</sup>
  • B Na<sup style='font-size: smaller;'>+</sup> and OH<sup style='font-size: smaller;'>-</sup>
  • C H<sup style='font-size: smaller;'>+</sup> and OH<sup style='font-size: smaller;'>-</sup>
  • D H<sup style='font-size: smaller;'>+</sup> and Cl<sup style='font-size: smaller;'>-</sup>
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Question 28:
CO(g) + H2O(g) → CO2(g) + H2(g)
From the reaction above, calculate the standard enthalpies of formation of CO2(g), H2O(g) and CO(g) in kJ mol-1 are -394, -242, and -110 respectively.
  • A -262 kJ mol<sup style='font-size: smaller;'>-1</sup>
  • B -42 kJ mol<sup style='font-size: smaller;'>-1</sup>
  • C +42 kJ mol<sup style='font-size: smaller;'>-1</sup>
  • D +262 kJ mol<sup style='font-size: smaller;'>-1</sup>
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Question 29:
When sugar is dissolved in tea, the reaction is always accomplished by
  • A Positive change
  • B Negative entropy change
  • C No entropy change
  • D A minimum entropy change
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Question 30:
Which of the following is an electrolyte?
  • A Alcohol
  • B Sodium acetate solution
  • C Solid potassium hydroxide
  • D Mercury
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