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: An increase in entropy can best be illustrated by Options:
  A) mixing of gases
  B) freezing of water
  C) the condensation of vapour
  D) solidifying candle wax
  Show Answer
  The correct answer is A .
• Question 12:

  The oxidation state(s) of nitrogen in ammonium nitrite is/are

  Options:
  A) -3, +3
  B) +5
  C) -3, +5
  D) -3
  Show Answer
  The correct answer is A .
• Question 13:

  n monosaccharide $\underset{Q}{\stackrel{P}{\rightleftharpoons }}$ polysaccharide -n water.

  In the process above, P and Q respectively represent

  Options:
  A) Condensation and hydrolysis
  B) Fermentation and condensation
  C) Polymerization and hydrolysis
  D) Polymerization and condensation
  Show Answer
  The correct answer is A .
• Question 14:

  A certain hydrocarbon on complete combustion at s.t.p produced 89.6dm${}^3$ of CO${}_2$ and 54g of water. The hydrocarbon should be

  Options:
  A) C${}_6$H${}_6$
  B) C${}_4$H${}_{10}$
  C) C${}_5$H${}_{10}$
  D) C${}_4$H${}_6$
  Show Answer
  The correct answer is D .
• Question 15: Which of the following raw materials would be required from the smelting of iron ore in a blast furnace? Options:
  A) CaCO ₃
  B) Zn(NO₃)₂
  C) CuSO₄
  D) AICI₃
  E) CaSO₄
  Show Answer
  The correct answer is A .
• Question 16: Which of the following pair of gases will NOT react further with oxygen at a temperature between 30^oC AND 400^oC Options:
  A) SO₂ and NH₃
  B) CO₂ and H₂
  C) NO₂ and SO₃
  D) SO₃ and NO
  E) CO and H₂
  Show Answer
  The correct answer is C .
• Question 17: Calculate the amount in moles of a gas which occupies 10.5 dm³ at 6 atm and 30^oC [R = 082 atm dm³ K^-1 mol^-1] Options:
  A) 2.536
  B) 1.623
  C) 4.736
  D) 0.394
  Show Answer
  The correct answer is A .
• Question 18: Which of the following statements is correct about the periodic table? Options:
  A) Elements in the same group have the same number of electron shells
  B) The non-metallic properties of the elements tend to decrease across each period
  C) Elements in the same period have the same number of valence electrons
  D) The valence electrons of the elements increase progressively across the period
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  The correct answer is D .
• Question 19:

  One of the following is not a physical property of monosaccharides?

  Options:
  A) Monosaccharides get charred when heated
  B) Monosaccharides are water-soluble, sweet substances
  C) They are highly vital to the exploration of metals
  D) They can be reduced to sugar alcohols
  Show Answer
  The correct answer is C .
• Question 20: CH₃CH₂Cl + KCN → CH₃CH₂CN + KClIn the reaction above, the cyanide is Options:
  A) hydrophobic
  B) hydrophilic
  C) nucleophilic
  D) electrophilic
  Show Answer
  The correct answer is C .