Chemistry Exam Past Questions and Answers | JAMB, WAEC and NECO

Chemistry is the study of the substances that make up matter. It looks at their properties, how they react with each other, and how these reactions can create new substances.

• Question 591:

  Na₂S₂O_3(aq) + 2HCl_(aq) → 2NaCl_(aq) + H₂O_(l)

  Which of the following would introduce the greatest increase in the rate of the chemical reaction above?

  Options:
  A) An increase in temperature and decrease in the concentration of the reactant
  B) A decrease in the volume and increase in the pressure of the reactant
  C) A decrease in the temperature and an incease in the concentration of the reactant
  D) An increase in temperature and an increase in the concentration of the reactant
  Show Answer
  The correct answer is D .
• Question 592:

  If 10.5g of lead (II) trioxonitrate (V) is dissolved in 20cm³ of distilled water at 18^oC, the solubility of the solute in mol dm^-3 is

  [Pb = 207, N = 14, O = 16]

  Options:
  A) 1.60
  B) 5.25
  C) 16.00
  D) 525.00
  Show Answer
  The correct answer is A .
• Question 593: The principal constituent of natural gas is Options:
  A) methane
  B) ethane
  C) propane
  D) Butane
  Show Answer
  The correct answer is A .
• Question 594: CH₃COOC₂H₅(1) + H₂O₍₁₎ ⇌ CH ₃COOH _(aq) + C ₂H ₅OH _(aq)The purpose of H⁺ in the reaction above is to Options:
  A) increase the yield of products
  B) maintain the solution at a constant PH
  C) increase the rate of the hydrolysis
  D) decrease the rate of the reverse reaction
  Show Answer
  The correct answer is A .
• Question 595: The arrangement of particles in crystal lattices can be studied using Options:
  A) X-rays
  B) $\beta$-rays
  C) $\alpha$-rays
  D) $\gamma$-rays
  Show Answer
  The correct answer is A .
• Question 596:

  The sub-atomic particles located in the nucleus of an atomare?

  Options:
  A) neutron and proton
  B) proton and electron
  C) proton and ions
  D) neutron and electron
  Show Answer
  The correct answer is A .
• Question 597: Which of the following best explains the increase in the rate of a chemical reaction as the temperature rises? Options:
  A) The bonds in the reacting molecules are more readily broken
  B) The molecular collisions become more violent
  C) A lower proportion of the molecules has the necessary minimum energy to react
  D) The collision frequency of the molecules increase
  Show Answer
  The correct answer is D .
• Question 598: What is the partial pressure of hydrogen gas collected over water at standard atmospheric pressure and 25^oC if the saturation vapour pressure of water at saturation vapour pressure of water is 23 mm Hg at that temperature? Options:
  A) 737 mm Hg
  B) 763 mm Hg
  C) 777 mm Hg
  D) 783 mm Hg
  Show Answer
  The correct answer is A .
• Question 599:

  2SO_2(g) + O_2(g) ↔ 2SO_3(g)

  ΔH = -189 kJ mol^-1

  The equilibrium constant for the reaction above is increased by

  Options:
  A) Increasing the temperature of the system
  B) Increase the pressure of the system
  C) The addition of a catalyst to the system
  D) Increasing the surface area of the vessel
  Show Answer
  The correct answer is B .
• Question 600: A change in the temperature of a saturated solution disturbs the equilibrium between the Options:
  A) Undissolved solute and the solvent
  B) Dissolved solute and the solvent
  C) Dissolved solute and the undissolved solute
  D) Dissolved solute and the solution
  Show Answer
  The correct answer is C .