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 1: A piece of sea shell, when dropped into a dilute solution of hydrochloric acid, produces a colourless, odourless gas which turns clear limewater milky. The sea shell contains Options:
  A) sodium chloride
  B) ammonium nitrate
  C) calcium carbonate
  D) calcium chloride
  E) magnesium chloride
  Show Answer
  The correct answer is C .
• Question 2:

  What is eutrophication?

  Options:
  A) The release of harmful chemicals into water bodies
  B) The excessive growth of algae due to nutrient enrichment
  C) The presence of heavy metals in water
  D) The formation of oil slicks on water surfaces
  Show Answer
  The correct answer is B .
• Question 3: A student prepares 0.5 M solution each of hydrochloric and ethanoic acids and then measured pH. The result would show that the? Options:
  A) pH values are equal
  B) HCI solution has a higher pH
  C) sum of the values is 14
  D) ethanoic acid solution has a higher pH
  Show Answer
  The correct answer is D .
• Question 4: A metal M displaces zinc from zinc chloride solution. This shows that Options:
  A) M is more electronegative than zinc
  B) Zinc is above hydrogen in the series
  C) M is more electropositive than zinc
  D) Electrons flow from zinc to M
  Show Answer
  The correct answer is C .
• Question 5: An aqueous solution of a metal salt, M, gives a white precipitate with NaOH which dissolves in excess NaOH. With aqueous ammonia, the solution of M also gives a white precipitate which dissolves in excess ammonia. Therefore cartion in M is Options:
  A) Zn ⁺⁺
  B) Ca⁺⁺
  C) Ai⁺⁺⁺
  D) Pb⁺⁺
  E) Cu⁺⁺
  Show Answer
  The correct answer is A .
• Question 6:

  An element X forms the following compounds with chlorine; XCl${}_4$, XCl${}_3$, XCl${}_2$. This illustrates the

  Options:
  A) law of multiple proportions
  B) law of chemical proportions
  C) law of simple proportions
  D) law of conservation of mass
  Show Answer
  The correct answer is A .
• Question 7:

  In the reaction:

  M + N → P

  ΔH = +Q kJWhich of the following would increase the concentration of the product?

  Options:
  A) Adding a suitable catalyst
  B) Increasing the concentration of P
  C) Increasing the temperature
  D) Decreasing the temperature
  Show Answer
  The correct answer is C .
• Question 8:

  In the preparation of salts, the method employed will depend on the?

  Options:
  A) composition
  B) dissociating ability
  C) stability to heat
  D) precipitating ability
  Show Answer
  The correct answer is C .
• Question 9: The air pollutant unknown in nature is Options:
  A) NO
  B) CO
  C) HCHO
  D) DDT
  Show Answer
  The correct answer is C .
• Question 10: When hydrogen sulphide and sulphur dioxide are each passed in turn into a solution of potassium dichromate? Options:
  A) both gases change the colour of the solution from yellow to colourless
  B) both gases causes sulphur to be deposited
  C) only hydrogen sulphide decolourizes the solution
  D) only sulphur dioxide deposits sulphur
  E) only hydrogen sulphide deposits sulphur
  Show Answer
  The correct answer is E .