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 911: Which of the following will change when a catalyst is added to a chemical reaction? Options:
  A) The activation energy
  B) The potential energy of the reactants
  C) The heat of the reaction
  D) the potential energy of the product
  Show Answer
  The correct answer is A .
• Question 912:

  With conc H₂SO₄ as catalyst

  CH₃COOH + C₂H₅OH → CH₃COOC₂H₅ + H₂O

  Options:
  A) esterification
  B) Condensation
  C) saponification
  D) neutralization
  Show Answer
  The correct answer is A .
• Question 913: In a water body, too much sewage leads to Options:
  A) a decrease in the temperature of the water which cause in death of aquatic animals
  B) an increase in the number of aquatic animals in the water
  C) an increase in the bacterial population which reduces the level of oxygen in the water
  D) a decrease in the bacterial population which increases the level of oxygen in the water
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  The correct answer is C .
• Question 914: POlyvinyl chloride is used to produce Options:
  A) bread
  B) pencils
  C) ink
  D) pipes
  Show Answer
  The correct answer is D .
• Question 915: The label on a reagent bottle containing a clear organic liquid dropped off.The liquid was neutral to litmus and gave a colourless gas with metallic sodium. The liquid must be an? Options:
  A) alkanoate
  B) alkaene
  C) alkanol
  D) alkane
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  The correct answer is C .
• Question 916: A solution of calcium bromide contains 20 g dm ³ What is the molarity of the solution with respect to calcium bromide and bromide ions? [Ca = 40, Br = 80] Options:
  A) 0. 1, 0 . 1
  B) 0. 1, 0. 2
  C) 0. 1, 0. 05
  D) 0.05, 0.1
  Show Answer
  The correct answer is C .
• Question 917:

  Zn _(s) + CuSO ₄(aq) → ZnSO ₄(aq) + Cu _(s)

  In the reaction above, the oxidation number of the reducing agent changes from

  Options:
  A) 0 to + 4
  B) 0 to + 2
  C) + 1 to + 2
  D) + 1 to + 3
  Show Answer
  The correct answer is B .
• Question 918: A sample of hard water contains some calcium sulphate and calcium hydrogen carbonate. The total hardness may therefore be removed by Options:
  A) boiling the water
  B) adding excess calcium hydroxide
  C) adding a calculated amount of calcium hydroxide
  D) adding sodium carbonate
  E) adding magnesium hydroxide
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  The correct answer is D .
• Question 919: 300 cm³ of gas has a pressure of 800 mmHg. If the pressure is reduced to 650 mmHg, find its volume Options:
  A) 243.75 cm³
  B) 369.23 cm³
  C) 738.46 cm³
  D) 1733.36 cm³
  Show Answer
  The correct answer is B .
• Question 920: The compounds CH₃CH₂CHO and CH₃COCH₃ can be distinguished from each other using Options:
  A) Dilute ammonia
  B) Benedict's solution
  C) Tollen's reagent
  D) Sodium hydroxide solution
  Show Answer
  The correct answer is C .