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 2161: Which of the following results in the fall of acid rain? Options:
  A) Oxides of lead
  B) Particulate matter
  C) Oxides of sulphur
  D) Gaseous hydrocarbon
  Show Answer
  The correct answer is C .
• Question 2162:

  A compound contains 31.91% potassium, 28.93% chlorine and the rest oxygen. What is the chemical formula of the compound?

  [K = 39, Cl = 35.5, O = 16]

  Options:
  A) KClO₄
  B) KClO
  C) KClO₂
  D) KClO₃
  Show Answer
  The correct answer is D .
• Question 2163:

  2KClO3(g) MNO3→ 2KCl(s) + 3O2(g)

  The importance of the catalyst in the reaction above is that

  Options:
  A) heating may not be required before the reaction takes place
  B) the reaction is controllable even at a high temperature
  C) the reaction produces large quantity of oxygen
  D) the reaction takes place more rapidly at a lower temperature
  Show Answer
  The correct answer is D .
• Question 2164:

  4g each of aluminium foil and aluminium powder were introduced respectively into flasks P and Q.

  Flask P was treated with warm bench sodium hydroxide and all the aluminium dissolved in one hour. Flask Q was treated with cold sodium hydroxide and all the aluminium dissolved in 10 minutes. What was responsible for Q reacting faster than P?

  Options:
  A) There were more aluminium atoms in Q than P
  B) The heat given off in retarded the reaction
  C) Q generated more pressure than P during the reaction
  D) P generated more pressure than Q
  E) Q has a greater surface area for the reaction than P
  Show Answer
  The correct answer is E .
• Question 2165: In an attempt to remove sugar from a breaker containing a quantity of sand and sugar, 2 M ammonium chloride solution was accidentally added instead of water. Which of the following method could be used to remove the ammonium chloride from the mixture? Options:
  A) Fractional distillation
  B) crystallization
  C) Filtration followed by evaporation
  D) Evaporation followed by sublimation
  E) Filtration followed by sublimation
  Show Answer
  The correct answer is D .
• Question 2166: Copper (II) tetraoxosulphate (IV) is widely used as a? Options:
  A) fertilizer
  B) fungicide
  C) disinfectant
  D) purifier
  Show Answer
  The correct answer is B .
• Question 2167:

  

  The arrangement above can be used for the collection of

  Options:
  A) sulphur (IV) oxide
  B) ammonia
  C) hydrogen chloride
  D) nitrogen
  Show Answer
  The correct answer is C .
• Question 2168:

  

  If in the graph above 1 dm³ of a saturated solution of KCL is cooled from 80^oC, the mass of crystals deposited will be  [K = 39, Cl = 35.5]

  Options:
  A) 7.45 g
  B) 14.90 g
  C) 74.50 g
  D) 149.00 g
  Show Answer
  The correct answer is D .
• Question 2169: Which of the following is formed when maltose reacts with concentrated tetraoxosulphate (VI) acid ? Options:
  A) Carbon (IV) oxide
  B) Coal tar
  C) Charcoal
  D) Toxic fumes
  Show Answer
  The correct answer is C .
• Question 2170: In an equilibrium reaction, which of the following conditions indicates that maximum yield of the product will be obtained? Options:
  A) Equilibrium constant is very large
  B) ∆H - T∆S = O
  C) ∆ H > T ∆ S
  D) Equilibrium constant is less than zero
  Show Answer
  The correct answer is A .