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 541:

  MnO^-4_(aq) + Y + 5Fe²⁺_(aq) → Mn²⁺_(aq) + 5Fe²⁺_(aq) + 4H₂O_(l)
  In the equation above, Y is

  Options:
  A) 5H⁺_(aq)
  B) 4H⁺_(aq)
  C) 10H⁺_(aq)
  D) 8H⁺_(aq)
  Show Answer
  The correct answer is D .
• Question 542: An elements used in production of matches is Options:
  A) nitrogen
  B) aluminum
  C) copper
  D) sulphur
  Show Answer
  The correct answer is D .
• Question 543:

  Which two gases can be used for the demonstration of the fountain experiment?

  Options:
  A) SO${}_3$ and NH${}_3$
  B) SO${}_2$ and NH${}_3$
  C) HCl and NH${}_3$
  D) SO${}_2$ and HCl
  Show Answer
  The correct answer is C .
• Question 544:

  The equilibrium reaction between copper (l) chloride and chlorine at 25^oC and 1 atmosphere is represented by the equation:

  2CuCl +Cl₂ ⇌ 2 CuCl₂ ∆H = - 166 KJ. Which of the following statements is TRUE for the reaction, pressure remaining constant?

  Options:
  A) more CuCl is formed at 40^oC
  B) more CuCl₂ is formed at 10^oC
  C) Less CuCl₂ is formed at 10^oC
  D) there is no change in the amount of CuCl₂ formed at 40^oC and10^oC
  E) more CuCl is consumed at 40^oC
  Show Answer
  The correct answer is B .
• Question 545: If 0.75 mole of cyclopropane and 0.66 mole of oxygen are mixed in vessel with a total pressure of 0.7 atmosphere, what is the partial pressure of oxygen in the mixture Options:
  A) 0.44 atmosphere
  B) 0.22 atmosphere
  C) 0.55 atmosphere
  D) 0.33 atmosphere
  Show Answer
  The correct answer is D .
• Question 546:

  Which separation technique is used to separate different pigments in a mixture based on their affinity for a stationary phase and a mobile phase?

  Options:
  A) Chromatography
  B) Filtration
  C) Decantation
  D) Distillation
  Show Answer
  The correct answer is A .
• Question 547: If an equilibrium reaction has ∆H < O, the reaction will proceed favorably in the forward reaction at? Options:
  A) low temperatures
  B) high temperatures
  C) all temperatures
  D) all pressures
  Show Answer
  The correct answer is A .
• Question 548:

  

  In the electrolysis of aqueous solution of K₂SO ₄ in the above cell, which species migrate to the anode?

  Options:
  A) SO^2-OH ^-
  B) K ⁺ and SO ₄^2-
  C) OH and HO
  D) H₃O ⁺ and K
  Show Answer
  The correct answer is A .
• Question 549:

  When an acidic solution is diluted, what happens to its pH?

  Options:
  A) It depends on the specific acid
  B) It decreases
  C) It remains the same
  D) It increases
  Show Answer
  The correct answer is D .
• Question 550:

  5cm³ of a saturated solution of sodium chloride at 30°C gave, on careful evaporation, 1.95g of solid salt. The solubility of sodium chloride at 30°C?

  (Na = 23, Cl = 35.5)

  Options:
  A) 5.00 mole dm³
  B) 5.67 mole dm³
  C) 6.00 mole dm³
  D) 6.67 mole dm³
  E) 7.00 mole dm³
  Show Answer
  The correct answer is D .