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 2241: The most common type of chemical reaction which alkanes undergo is Options:
  A) substitution
  B) addition
  C) condensation
  D) polymerisation
  E) double decomposition
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  The correct answer is A .
• Question 2242: The pair of metals in the reactivity series that are usually extracted by the electrolysis of their ores is Options:
  A) magnesium and zinc
  B) magnesium and calcium
  C) copper and zinc
  D) lead and calcium
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  The correct answer is B .
• Question 2243: The energy value of petrol can be determined by a Options:
  A) bomb calorimeter
  B) catalytic cracker
  C) fractionating column
  D) thermometer
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  The correct answer is C .
• Question 2244: CH₃CH₂Cl + KCN → CH₃CH₂CN + KClIn the reaction above, the cyanide is Options:
  A) hydrophobic
  B) hydrophilic
  C) nucleophilic
  D) electrophilic
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  The correct answer is C .
• Question 2245:

  Chlorine gas is commonly used in the production of which of the following industrial compounds?

  Options:
  A) Chlorofluorocarbons (CFCs)
  B) Methane
  C) Ammonia
  D) Ethanol
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  The correct answer is A .
• Question 2246:

  The Sulphide which is insoluble in dilute hydrochloric acid is

  Options:
  A) FeS
  B) CuS
  C) ZnS
  D) Na2S
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  The correct answer is B .
• Question 2247: The salt that reacts with dilute hydrochloric acid to produce a pungent smelling gas which decolourizes acidified purple potassium tetraoxomanganate (VII) solution is Options:
  A) Na₂SO₄
  B) Na₂SO₃
  C) Na₂S
  D) Na₂CO₃
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  The correct answer is B .
• Question 2248: The pH of a solution obtained by mixing 100cm³ of a 0.2M solution of NaOH is? Options:
  A) 1.3
  B) 7.0
  C) 9.7
  D) 12.7
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  The correct answer is D .
• Question 2249: Which of the following does NOT happen when a zinc rod is introduced into a solution of copper (ll) sulphate? Options:
  A) Electrons flow towards the zinc rod
  B) The zinc rod dissolves
  C) The temperature of the soil changes
  D) The blue colour of the solution gradually disappears
  E) Copper metal is deposited
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  The correct answer is A .
• Question 2250: Which of the following compounds will form a solution if exposed to air? Options:
  A) Na₂CO₃.10H₂O
  B) NaNO₃
  C) CuSO₄
  D) CaCl₂
  E) Na₂SO₄.10H₂O
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  The correct answer is D .