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 91: Which of the following compounds will impart a brick-red colour to a non-luminious bunsen flame? Options:
  A) NaCl
  B) LiCl
  C) CaCl₂
  D) MgCl₂
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  The correct answer is C .
• Question 92: The enzyme used in the hydrolysis of starch to dextrin and maltose is Options:
  A) amylase
  B) diastatse
  C) invertase
  D) zymase
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  The correct answer is B .
• Question 93: Millikan's contributions to the development of atomic theory is the determination of Options:
  A) charge on electron
  B) positive rays
  C) charge to mass ratio
  D) cathode rays
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  The correct answer is A .
• Question 94: CH₃COOC₂H₅(1) + H₂O₍₁₎ ⇌ CH ₃COOH _(aq) + C ₂H ₅OH _(aq)The purpose of H⁺ in the reaction above is to Options:
  A) increase the yield of products
  B) maintain the solution at a constant PH
  C) increase the rate of the hydrolysis
  D) decrease the rate of the reverse reaction
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  The correct answer is A .
• Question 95: The boiling point of water, ethanol, toluene and butan-2-ol are 373.0k, 351.3k, 383.6k and 372.5k respectively. Which liquid has the highest vapour pressure at 323.0k? Options:
  A) water
  B) toluene
  C) ethanol
  D) butan-2-ol
  E) none
  Show Answer
  The correct answer is C .
• Question 96: 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
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  The correct answer is D .
• Question 97: A difference between chemical and physical change is that in a chemical change Options:
  A) oxygen is consumed
  B) heat is supplied
  C) the reversible process occurs
  D) a new substance is formed
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  The correct answer is D .
• Question 98:

  Which functional group is present in alkanals?

  Options:
  A) Carbonyl group (C=O)
  B) Hydroxyl group (-OH)
  C) Alkyl group (-R)
  D) Carboxyl group (-COOH)
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  The correct answer is A .
• Question 99: In which of the following reactions is sulphur dioxide acting as an oxidizing agent? Options:
  A) SO ₂ + 2HNO₃ →H₂SO₄ + NO₂ + Heat
  B) 2SO₂ + 2H₂O + O₂→ 2H₂SO₄
  C) SO₂ + 2H₂O + CI₂→ H₂SO₄ + 2HCI
  D) SO₂ + 2H₂S → 3S + 2H₂O
  E) SO₂ + H₂O → H₂SO₃
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  The correct answer is D .
• Question 100:

  A chemical reaction in which the hydration energy is greater than the lattice energy is referred to as

  Options:
  A) A reversible reaction
  B) A spontenous reaction
  C) An endothermic reaction
  D) An exothermic reaction
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  The correct answer is D .