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 1681: Which of the following separation processes is most likely to yield high quality ethanol (>95%) from palm wine? Options:
  A) Fractional distillation without a dehydrant
  B) simple distillation with a dehydrant
  C) fractional distillation with a dehydrant
  D) column chromatography
  E) evaporation
  Show Answer
  The correct answer is C .
• Question 1682: A compound contains 40.0% carbon, 6.7% hydrogen and 53.3% oxygen. If the molar mass of the compound is 180, Find the molecular formula [H = 1, C = 12, O = 16) Options:
  A) CH₂O
  B) C₃H₆O₃
  C) C₆H₁₂O₆
  D) C₆H₁₂O₃
  Show Answer
  The correct answer is C .
• Question 1683: The acid used in electrolysis of water is dilute Options:
  A) HNO₃
  B) CH₃COOH
  C) H₂SO₄
  D) HCl
  Show Answer
  The correct answer is C .
• Question 1684:

  An organic compound X has the following properties:
  I. It is not miscible with water.
  ll. It has boiling point of 77^oC.
  lll. It has a sweet odour.
  IV. lt is insoluble in sodium hydrogen carbonate solution.
  V lt does not decolourize bromine water.
  X is therefore

  Options:
  A) methane
  B) ethanoic acid
  C) ethene
  D) ethyl ethanoate
  E) carbon tetrachloride
  Show Answer
  The correct answer is D .
• Question 1685:

  The volume of 2.5 moles of oxygen at s.t.p is

  [Molar volume of a gas at s.t.p = 22.4 dm³]

  Options:
  A) 50.0 dm³
  B) 84.0 dm³
  C) 28.0 dm³
  D) 56.0 dm³
  Show Answer
  The correct answer is D .
• Question 1686: Clothes should be properly rinsed with water after bleaching because Options:
  A) the bleach decolourizes the clothes
  B) chlorine reacts with fabrics during bleaching
  C) the clothes are sterilized during bleaching
  D) hydrogen chloride solution is produced during bleaching
  Show Answer
  The correct answer is D .
• Question 1687: The gas that can best be collected by downward displacement of air is Options:
  A) Chlorine
  B) Sulphur (IV) oxide
  C) Ammonia
  D) Carbon (IV) oxide
  Show Answer
  The correct answer is C .
• Question 1688:

  The Sulphide which is insoluble in dilute hydrochloric acid is

  Options:
  A) FeS
  B) CuS
  C) ZnS
  D) Na2S
  Show Answer
  The correct answer is B .
• Question 1689: In the laboratory preparation of trioxonitrate (V) acid the nitrogen(iv) oxide formed as a by-product is removed by Options:
  A) further heating
  B) adding concentrated H₂SO₄
  C) cooling the acid solution with cold water
  D) bubbling air through the acid solution
  Show Answer
  The correct answer is D .
• Question 1690: What is the concentration of H⁺ ions in moles per dm³ of a sodium of pH 4.398? Options:
  A) 4.0 χ 10^-5
  B) 0.4 χ 10^-5
  C) 4.0 χ 10^-3
  D) 0.4 χ 10^-3
  Show Answer
  The correct answer is A .