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 1: Which of the following statement is correct about the periodic table? Options:
  A) Elements in the same period have the same number of valency electron
  B) The valence electron of the elements in the same period increase progressively across the period
  C) Elements in the same group have the same number of electron shells
  D) The non-metallic properties of the elements tend to decrease across each period
  Show Answer
  The correct answer is B .
• Question 2: SO₃ is NOT directly dissolved in water in the preparation of H₂SO₄ by the contact process because? Options:
  A) the reaction between SO₃ and water is violently exothermic
  B) acid is usually added to water and never water to acid
  C) SO₃ does not dissolve in water readily
  D) SO₃ is an acid gas
  Show Answer
  The correct answer is A .
• Question 3: The best way of collecting chlorine is? Options:
  A) by downward displacement of air
  B) by upward displacement of air
  C) over water
  D) under water
  E) over mercury
  Show Answer
  The correct answer is B .
• Question 4: Steam changes the colour of anhydrous cobalt (ll) chloride from Options:
  A) white to red
  B) blue to white
  C) blue to pink
  D) white to blue
  Show Answer
  The correct answer is C .
• Question 5:

  Which of the following pollutants will lead to the depletion of ozone layer?

  Options:
  A) chlorofluorocarbon
  B) carbon (ii) oxide
  C) hydrogen sulphide
  D) sulphur (iv) oxide
  Show Answer
  The correct answer is A .
• Question 6: Alkanals can be distinguished from alkanones by the reaction with Options:
  A) sudan lll stain
  B) starch iodide paper
  C) lithium tetrahydrido aluminate (lll)
  D) fehling's solution
  Show Answer
  The correct answer is D .
• Question 7:

  

  The IUPAC nomenclature of the structure is

  Options:
  A) 3-chloro-3-methylbutane
  B) 2,2,-dichloro-3-methylbutane
  C) 3-methylchlorobutane
  D) 2-chloro-2-methylbutane
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  The correct answer is D .
• Question 8: On heating, under suitable conditions, 1 litres of monoatomic gas,X, combines with 1¹/₂ litres of an oxide, What is the formula of the oxide. Options:
  A) XO₃
  B) X₂O₃
  C) X₃O₂
  D) XO₂
  E) None of the above
  Show Answer
  The correct answer is B .
• Question 9: The energy value of petrol can be determined by Options:
  A) Bomb calorimeter
  B) Catalytic cracker
  C) Fractionating column
  D) Thermometer
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  The correct answer is C .
• Question 10: 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 .