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 11:

  Which of the following does not support the fact that air is a mixture?

  Options:
  A) the constituents of air are in a fixed proportion by mass
  B) it cannot be represented with a chemical formula
  C) the constituents of air can be separated by physical by physical means
  D) none of the above
  Show Answer
  The correct answer is A .
• Question 12:

  

  From the diagram above, find the amount of solute deposited when 200 cm³ of the solution is cooled from 55^oC to 40^oC

  Options:
  A) 0.10 mole
  B) 0.20mole
  C) 0.01 mole
  D) 0.02 mole
  Show Answer
  The correct answer is B .
• Question 13: When 50cm³ of a saturated solution of sugar (molar mass 342.0g) at 40^oC was evaporated to dryness, 34.2g of dry solid was obtained. The solubility of sugar at 40^oC is Options:
  A) 10.0 moles dm^-3
  B) 7.0 moles dm^-3
  C) 3.5 moles dm^-3
  D) 2.0 moles dm^-3
  Show Answer
  The correct answer is D .
• Question 14: Which of the following ions is a pollutant in drinking water even in trace amounts? Options:
  A) Ca²⁺
  B) Hg²⁺
  C) Mg²⁺
  D) Fe²⁺
  Show Answer
  The correct answer is B .
• Question 15:

  The contact process is used for the industrial production of

  Options:
  A) sulfuric acid (H2SO4)
  B) Hydrochloric acid (HCl)
  C) Sodium hydroxide (NaOH)
  D) Calcium oxide (CaO)
  Show Answer
  The correct answer is A .
• Question 16: The structural component that makes detergent dissolve more quickly in water than soap is Options:
  A) -SO₃- Na⁺
  B) -COO-Na^-
  C) -SO₄- Na⁺
  D) -COO-K⁺
  Show Answer
  The correct answer is A .
• Question 17: Calculate the number of moles of HCl present in 20cm³ of a 0.75M solution of the acid Options:
  A) 0.015 mole
  B) 0.038 mole
  C) 3.800 moles
  D) 1.500 moles
  Show Answer
  The correct answer is A .
• Question 18: The salt formed from a weak acid and a strong base hydrolyzes in water to form Options:
  A) A saturated solution
  B) an acidic solution
  C) a buffer solution
  D) an alkaline solution
  Show Answer
  The correct answer is D .
• Question 19:

  What type of reaction is involved in the formation of alkanols from alkenes?

  Options:
  A) Elimination reaction
  B) Redox reaction
  C) Substitution reaction
  D) Addition reaction
  Show Answer
  The correct answer is D .
• Question 20: Hardness of water is mainly due to the presence of Options:
  A) calcium hydroxide or magnesium hydroxide
  B) calcium trioxocarbonate (IV) or calcium tetraoxosulphate (VI)
  C) sodium hydroxide or magnesium ydroxide
  D) calcium chloride or sodium chloride salts
  Show Answer
  The correct answer is B .