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 591: In the course of purifying water for town supply the water is passed through large settlings tanks, containing sodium aluminate (III) to remove Options:
  A) large particles
  B) germs
  C) fine particles
  D) odour
  Show Answer
  The correct answer is A .
• Question 592:

  Which of the following is an example of a chemical change?

  Options:
  A) dissolution of salt in water
  B) rusting of iron
  C) melting of ice
  D) separating a mixture by distillation
  Show Answer
  The correct answer is B .
• Question 593: 3.0g of a mixture of potassium carbonate and potassium chloride were dissolved in a 25cm³ of this solution required required 40.00cm₃ of 0.1M HCl for neutralization. What is the percentage by weight of K₂CO₃ in the mixture. (K = 39, O = 16, C = 12) Options:
  A) 60
  B) 72
  C) 82
  D) 89
  E) 92
  Show Answer
  The correct answer is E .
• Question 594: The pOH of a solution of 0.25 mol dm^-3 of hydrochloric acid is Options:
  A) 12.40
  B) 13.40
  C) 14.40
  D) 14.60
  Show Answer
  The correct answer is B .
• Question 595: A gas exerts pressure on its container because Options:
  A) some of its molecules are moving faster than others
  B) of the collision of the molecules with each other
  C) of the mass of the molecules of gas
  D) the molecules of a gas colide with the walls of the container
  Show Answer
  The correct answer is D .
• Question 596: A pair of compounds that can be used to generate a gas which has physiological effect on human beings is Options:
  A) sodium trioxonitrate (V) and calcium chloride
  B) sodium dioxonitrate (III) and ammonium chloride
  C) sodium trioxonitrate (V) and ammonium chloride
  D) sodium dioxonitrate (III) and potassium chloride
  Show Answer
  The correct answer is A .
• Question 597:

  The ionic radii of metals are usually

  Options:
  A) greater than their atomic radii
  B) unaffected by the charge on the ion
  C) the same as their atomic radii
  D) less than their atomic radii
  Show Answer
  The correct answer is D .
• Question 598: Iron galvanized with zinc is cathodically protected from corrosion. This is because? Options:
  A) zinc has a more positive oxidation potential than iron
  B) zinc has less positive oxidation potential than iron
  C) bith have the same oxidation potential
  D) zinc is harder than iron
  Show Answer
  The correct answer is B .
• Question 599: In the industrial production of hydrogen from natural gas, carbon (IV) oxide produced along with the hydrogen is removed by? Options:
  A) washing under pressure
  B) passing the mixture into lime water
  C) using ammoniacal copper (l) chloride
  D) drying over phoshorus (V) oxide
  Show Answer
  The correct answer is C .
• Question 600: How many isomers does pentane have? Options:
  A) 6
  B) 5
  C) 4
  D) 3
  Show Answer
  The correct answer is D .