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 41: In the preparation of ammonia, which of the following is used as the drying agent? Options:
  A) CaO
  B) CaCI₂
  C) Conc. H₂SO₄
  D) P₂O₅
  E) H₃PO₄
  Show Answer
  The correct answer is A .
• Question 42: The pollutant that contributes to the depletion of the ozone layer is Options:
  A) CFCs
  B) NO₂
  C) SO₂
  D) CO
  Show Answer
  The correct answer is A .
• Question 43: Which of the following compounds will undergo polymerization reaction? Options:
  A) C₂H₄
  B) C₂H₅COOH
  C) C₂H₆
  D) C₂H₅OH
  Show Answer
  The correct answer is A .
• Question 44: A catalyst increase the rate of a chemical reaction by providing a path that Options:
  A) raise the activiation energy
  B) increase the temperature
  C) lowers the activation energy
  D) increase the concentration
  Show Answer
  The correct answer is C .
• Question 45: If concentrated sulphric acid is added to sugar and warmed gently, the sugar changes from white to brown and finally to a black mas of carbon. In this reaction, concentrated sulphuric acid is acting as ? Options:
  A) a drying agent
  B) an oxidizing agent
  C) a dehydrated agent
  D) a reducing agent
  E) a hydrolysing agent
  Show Answer
  The correct answer is C .
• Question 46: The solubility product of Cu(IO₃)₂ is 1.08 * 10^-7. Assuming that neither ions react appreciable with water to form H⁺ and OH^-, what is the solubility of this salt? Options:
  A) 2.7 * 10^-8 mol dm^-3
  B) 9.0 * 10^-8 mol dm^-3
  C) 3.0 * 10^-3 mol dm^-3
  D) 9.0 * 10^-3 mol dm^-3
  Show Answer
  The correct answer is D .
• Question 47:

  SO${}_3$ is not directly dissolved in water in the industrial preparation of H${}_2$SO${}_4$ by the contact process because

  Options:
  A) SO${}_3$ is an acidic gas
  B) Acid is usually added to water and not water to acid
  C) The reaction between SO${}_3$ and water is violently exothermic
  D) SO${}_3$ does not dissolve readily in water
  Show Answer
  The correct answer is C .
• Question 48: In which of the following are water molecules in the most disorderly arrangement? Options:
  A) Ice at -10°C
  B) Ice at 0°C
  C) Water at 100°C
  D) Steam at 100°C
  Show Answer
  The correct answer is D .
• Question 49: When copper (ii) sulphate solution is treated with excess ammonium hydroxide, a precipitate is first formed, and then this dissolves to give a deep blue solution. This deep blue solution is a Options:
  A) Cu(OH)₂
  B) CuSo₄.5H₂O
  C) (NH₄)₂SO₄
  D) Cu(NH₃)₄(OH)₂
  E) CuSO₄.(NH₄)₂SO₄.2H₂O
  Show Answer
  The correct answer is E .
• Question 50: A suitable solvent for iodine and nephthalene is Options:
  A) carbon (IV) sulphide
  B) ethanol
  C) water
  D) benzene
  Show Answer
  The correct answer is B .