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 1421: The balanced equation for the reaction of tetraoxosulphate(VI)acid with aluminium hydroxide to give water and aluminium tetraoxosulphate(VI) is Options:
  A) H₂SO₄ + Al(OH)₂ $\to$ 2H₂O + AlSO₄
  B) 3H₂SO₄ + 2Al(OH)₃ $\to$ 6H₂O + Al₂(SO₄)₃
  C) 3H₂SO₄ + 2AlH $\to$ 6H₂O + Al(SO₄)₃
  D) 3H₂ SO₄ + 2Al(OH)₃ $\to$ Al(SO₄)₃
  E) H₂SO₄ + Al(OH)₃ $\to$ H₂O + Al₂(SO₄)₃
  Show Answer
  The correct answer is B .
• Question 1422: A mixture of petrol and water can be separated through Options:
  A) centrifugation
  B) distillation
  C) the use of separating funnel
  D) the use of filter paper
  Show Answer
  The correct answer is C .
• Question 1423:

  If the heat of combustion of hydrogen is -285.8kJ,

  What is the heat of formation of water?

  Options:
  A) +571.6 kJ
  B) -571.6 kJ
  C) -285.8 kJ
  D) +285.8 kJ
  Show Answer
  The correct answer is C .
• Question 1424:

  Consider the reaction: A + 2B${}_{(g)}\rightleftharpoons$ 2C + D${}_{(g)}$ ($\mathrm{\Delta }$H = +ve)

  What will be the effect of decrease in temperature on the reaction?

  Options:
  A) Rate of backward reaction will increase
  B) The equilibrium constant will shift
  C) Rates of forward and backward reactions are not affected
  D) Rate of forward reaction will increase
  Show Answer
  The correct answer is A .
• Question 1425: Which of the following would support the conclusion that a solid sample is a mixture? Options:
  A) the solid can be ground to a fine powder
  B) the density of the solid is 2.25 g dm³
  C) the solid has a melting range of 300^oC to 375^oC
  D) the solid absorbs moisture from the atmosphere
  Show Answer
  The correct answer is C .
• Question 1426:

  The process or act of extracting a metal from its ore and refining it is called?

  Options:
  A) Extraction
  B) Metal mining
  C) Mettallurgy
  D) Prospecting
  Show Answer
  The correct answer is C .
• Question 1427: Which of the following metals is passive to concentrated trioxonitrate (V) acid? Options:
  A) Iron
  B) Tin
  C) Copper
  D) Zinc
  Show Answer
  The correct answer is A .
• Question 1428: The ion that will give a white precipitate with aqueous NaOH and soluble in excess of the base is Options:
  A) Ca²⁺
  B) Mg²⁺
  C) Zn²⁺
  D) Cu²⁺
  Show Answer
  The correct answer is C .
• Question 1429: Which of the following statements is true? When the potassium atom forms its ion Options:
  A) it gains one electron and becomes neutral
  B) its atomic number decreases
  C) it achieves electronic configuration of orgon
  D) it loses one proton
  E) it loses one neutron
  Show Answer
  The correct answer is C .
• Question 1430:

  Addition of sodium chloride to water to form a solution would lead to?

  Options:
  A) increase in freezing point and increase the boiling point
  B) increase in freezing point and decrease the boiling point
  C) decrease in freezing point and decrease the boiling point
  D) decrease in freezing point and increase the boiling point
  Show Answer
  The correct answer is D .