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Friday, 22 May 2026
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Chemistry Past Questions and Answers

Jamb 1991 Chemistry Questions

Question 26:
2H2S(g) + SO2(g) → 3S(s) + 2H2O(I). The above reaction is?
  • A A redox reaction H<sub style='font-size: smaller;'>2</sub>S is the oxidant and SO<sub style='font-size: smaller;'>2</sub> is the reductant
  • B A redox reaction in which SO<sub style='font-size: smaller;'>2</sub> is the oxidant and H<sub style='font-size: smaller;'>2</sub>S is the reductant
  • C Not a redox reaction because there is no oxidant in reaction equation
  • D Not a redox because there is no reductant in the reaction equation
View Answer & Explanation
Question 27:
Magnesium (IV) oxide is known to hasten the decomposition of hydrogen peroxide. Its main action is to?
  • A Increase the surface area of the reactants
  • B Increase the concntration of the reactants
  • C Lower the activation energy for the reaction
  • D Lower the heat of reaction, ∆H, for the reaction
View Answer & Explanation
Question 28:
1.1 g of CaCI2 dissolved in 50 cm3 of water caused a rise in temperature of3.4°C. The heat of reaction, ∆H for CaCI2 in kj per mole is?
(Ca = 40, CI = 35.5, specific heat of water is 4.18 jk-1
  • A -71.1
  • B -4.18
  • C +71.1
  • D +111.0
View Answer & Explanation
Question 29:
NO(g) + CO(g) ↔ (1)/(2)N2(g) + CO2(g) ∆H = -89.3 kj.
What conditions would favour maximum conversion of nitrogen (II) oxide and carbon (II) oxide in the reaction above?
  • A Low temperature and high pressure
  • B High temperature and low pressure
  • C High temperature and high pressure
  • D Low temperature and low pressure
View Answer & Explanation
Question 30:
Which of the following equilibria is unaffected by a pressure change?
  • A 2NaCI(s) ↔ 2Na <sub style='font-size: smaller;'>(I)</sub> + CI<sub style='font-size: smaller;'>2(g)</sub>
  • B H <sub style='font-size: smaller;'>2(g)</sub> + I<sub style='font-size: smaller;'>2(g)</sub> ↔ 2HI<sub style='font-size: smaller;'>(g)</sub>
  • C 2O<sub style='font-size: smaller;'>3(g)</sub> ↔ 3O<sub style='font-size: smaller;'>2(g)</sub>
  • D 2NO<sub style='font-size: smaller;'>2(g)</sub> ↔ N<sub style='font-size: smaller;'>2</sub>O<sub style='font-size: smaller;'>4(g)</sub>
View Answer & Explanation