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 1821: Rare gases are suitable because they Options:
  A) are monoatomic
  B) form ions easily
  C) have duplet or octet electronic configuration in the outermost shells in their atoms
  D) are volatile gases
  Show Answer
  The correct answer is C .
• Question 1822: The most suitable metal that can be used as lightning conductor is Options:
  A) silver
  B) copper
  C) iron
  D) aluminium
  Show Answer
  The correct answer is B .
• Question 1823:

  Some copper (ll) sulphate pentahydrate (CuSO₄ 5H₂O), was heated at 120 ^oC with the following results. Wt of crucible = 10.00 g; Wt of crucible + CuSO₄ 5H₂O =14.98g; Wt of crucible + residue = 13.54 g. How many molecules of water of crystalization were lost?

  [H = 1, Cu = 63.5, O = 16, S = 32]

  Options:
  A) 1
  B) 2
  C) 3
  D) 4
  E) 5
  Show Answer
  The correct answer is D .
• Question 1824: The electronic configuration of elements X and Y are X = 2, 8, 6; Y = 2, 8, 7. The bond in the compound formed by X and Y is expected to be? Options:
  A) ionic
  B) covalent
  C) dative covalent
  D) metallic
  E) none of the above
  Show Answer
  The correct answer is B .
• Question 1825: 50 cm³ of sulphur (IV) oxide, 800 cm³ of ammonia, 450 cm³ of hydrogen chloride, 1.0 cm³ of at 15°C. Which of the following is suitable for demonstrating the fountain experiment? Options:
  A) Sulphur (IV) oxide hydrogen chloride
  B) Carbon (IV) oxide and amonia
  C) Amonia and hydrogen chloride
  D) Carbon (IV) oxide and surphur (IV) oxide
  Show Answer
  The correct answer is C .
• Question 1826: The solubility of copper (II) tetraoxosulphate (Iv) is 75g in 100g of water at 100°C and 25g in 100g of water at 30°C. What mass of the salt would crystallize, if 50g of copper (II) tetraoxosulphate (VI) solution saturated at 100°C were cooled to 30°C ? Options:
  A) 57.5
  B) 42.2
  C) 28.6
  D) 14.3
  Show Answer
  The correct answer is D .
• Question 1827:

  If gas A has a molar mass of 32 g/mol and gas B has a molar mass of 64 g/mol, what is the ratio of their diffusion rates?

  Options:
  A) 2:1
  B) 1:2
  C) 1:1
  D) 1:4
  Show Answer
  The correct answer is A .
• Question 1828: A metal X forms two bromides with the formulae XBr₂ and XBr₃. What type of bonding exists between X and bromine in the bromide? Options:
  A) Ionic bonding
  B) Metallic bonding
  C) Dative bonding
  D) Covalent bonding
  Show Answer
  The correct answer is A .
• Question 1829: Solid sodium hydroxide on exposure to air absorbs a gas and ultimately gives another alkaline substance with the molecular formula? Options:
  A) NaOH.H₂O
  B) NaOH.N₂
  C) Na₂CO₃O
  D) NaHCO₃
  E) NaNO₃O
  Show Answer
  The correct answer is C .
• Question 1830: When ammonia and hydrogen ion bond together to form ammonium ion, the bond formed is called Options:
  A) ionic bond
  B) electrovalent bond
  C) covalent bond
  D) co-ordinate bond
  E) hydrogen bond
  Show Answer
  The correct answer is D .