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 1551: What is the decrease in volume of air when pyrogallol is shaken with 30.00cm³ of air ? Options:
  A) 15.00cm³
  B) 6.30cm³
  C) 0.63cm³
  D) 0.06cm³
  Show Answer
  The correct answer is B .
• Question 1552:

  The products of the thermal decomposition of ammonium trioxonitrate(v) are?

  Options:
  A) Nitrogen (I) Oxide and Water
  B) Ammonia and Oxide
  C) Nitrogen and Water
  D) Nitrogen (IV) Oxide and Water
  Show Answer
  The correct answer is A .
• Question 1553: If 100cm³ of oxygen pass through a porous plug is 50 seconds, the time taken for the same volume of hydrogen to pass through the same porous plug is? [O = 16, H = 1] Options:
  A) 10.0s
  B) 12.5s
  C) 17.7s
  D) 32.0s
  Show Answer
  The correct answer is B .
• Question 1554: Elements P, Q, R, S have 6, 11, 15, 17 electrons respectively, therefore, Options:
  A) P will form an electrovalent bond with R
  B) Q will form a covalent bond with S
  C) R will form an electrovalent bond with S
  D) Q will form an electrovalent bond with S
  E) Q will form a covalent bond with R
  Show Answer
  The correct answer is D .
• Question 1555: To make coloured glasses, small quantities of oxides of metals which form coloured silicates are often added to the reaction mixture consisting of Na₂CO₃ and SiO₂. Such a metals is a?. Options:
  A) pottasium
  B) barium
  C) zinc
  D) copper
  Show Answer
  The correct answer is D .
• Question 1556:

  

  50 cm³ of sulphur (lV) oxide, 800 cm³ of carbon (IV) oxide will respectively saturate 1.0cm³ of water at 15^oC. Which of the following is suitable for demonstrating the fountain experiment?

  Options:
  A) Sulphur (IV) oxide and hydrogen chloride.
  B) Carbon (IV) oxide and ammonia
  C) Ammonia and hydrogen chloride
  D) Carbon (IV) oxide and Sulphur (IV) oxide
  Show Answer
  The correct answer is C .
• Question 1557: Consider the following exothermic reaction 2SO₂(g) + O₂(g) = 2SO₃ (g) . If the temperature of the reaction is reduced from 800_oC to 500_oC, and no other change takes place, then Options:
  A) the reaction rate increases
  B) concentration of SO₃ decreases
  C) concentration of SO₃ increases
  D) SO₂ gas becomes unreactive
  E) O₂ gas becomes unreactive
  Show Answer
  The correct answer is C .
• Question 1558: A compound that will NOT produce oxygen on heating is? Options:
  A) potasium dioxonitrate (III)
  B) lead (IV) oxide
  C) potassium trioxochlorate (V)
  D) potassium trioxonitrate (V)
  Show Answer
  The correct answer is A .
• Question 1559:

  Which of the following is a common laboratory indicator for bases?

  Options:
  A) Methyl orange
  B) Phenolphthalein
  C) Bromothymol blue
  D) Litmus
  Show Answer
  The correct answer is B .
• Question 1560: Some metals are extracted from their ores after some preliminary treatments by electrolysis (L), some of both processes (TL). Which set-up in the following for the extraction of ion, copper and aluminium is correct? Options:
  A) lron (L), copper (L) aluminium (T)
  B) lron (T) copper (L) aluminium (T)
  C) lron (TL) copper (TL) aluminium (TL)
  D) Iron (L) copper (T) aluminium (T)
  E) lron (T) copper (L), aluminium (TL)
  Show Answer
  The correct answer is E .