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 1641: Chlorine gas is prepared in the laboratory by Options:
  A) adding concentrated hydrochloric acid to solid manganese (IV) oxide
  B) aciding concentrated tetraoxosulphate (VI) acid to solid sodium chloride
  C) dropping concentrated hydrochloric acid onto potassium tetraoxomanganate (VI) crystals
  D) aciding concentrated tetraoxosulphate (VI) acid to hydrochloric acid
  Show Answer
  The correct answer is A .
• Question 1642: Some products of destructive distillation of coal are Options:
  A) carbon (IV) oxide and ethanoic acid
  B) trioxocarbonate (IV) acid and methanoic acid
  C) producer gas and water gas
  D) coke and ammonia liquor
  Show Answer
  The correct answer is D .
• Question 1643: The combustion of ethene, C ₂H ₄, is given by the equation C ₂H ₄ + 30 ₂ → 2CO₂ + 2H₂ O; ∆H = - 1428 KJ. If the molar heats of formation of water and carbon (IV) oxide are - 286 kJ and - 396 kJ respectively, calculate the molar heat of formation of ethene in KJ Options:
  A) - 2792
  B) + 2792
  C) - 64
  D) + 64
  Show Answer
  The correct answer is D .
• Question 1644: A characteristic of the alkane family is Options:
  A) Addition reaction
  B) Elimination reaction
  C) Substitution reaction
  D) Neutralization reaction
  Show Answer
  The correct answer is C .
• Question 1645: Using 50 cm ³ of 1 M potassium hydroxide and 100cm ³ of 1 M tetraoxosulphate (VI) acid, calculate the respective volumes in cm ³ of base and acid that would be required to produce the maximum amount of potassium tetraoxosulphate (IV) [ = 39, S = 32, O = 16, H = 1] Options:
  A) 50, 50
  B) 25, 50
  C) 50, 25
  D) 25, 25
  Show Answer
  The correct answer is D .
• Question 1646:

  Cr₂O$\frac{2-}{7}$ (aq) + H₂O(1)⇌ 2CrO $\frac{2-}{4}$ (aq) + 2H ⁺ (aq)

  What happens to the reaction above when the hydrogen ion concentration is increased?

  Options:
  A) more of the products will be formed
  B) the reaction will not proceed
  C) the equilibrium position will shift to the right
  D) the equilibrium position will shift to the left.
  Show Answer
  The correct answer is D .
• Question 1647: When air is compressed? Options:
  A) its density decreases
  B) it solidifies
  C) its temperature decreases
  D) its temperature increases
  E) its temperature remains unchanged
  Show Answer
  The correct answer is C .
• Question 1648: When copper (ii) sulphate solution is treated with excess ammonium hydroxide, a precipitate is first formed, and then this dissolves to give a deep blue solution. This deep blue solution is a Options:
  A) Cu(OH)₂
  B) CuSo₄.5H₂O
  C) (NH₄)₂SO₄
  D) Cu(NH₃)₄(OH)₂
  E) CuSO₄.(NH₄)₂SO₄.2H₂O
  Show Answer
  The correct answer is E .
• Question 1649:

  What is the product of the electrolysis of aqueous sodium chloride (NaCl) using inert electrodes?

  Options:
  A) Hydrogen gas at the cathode and chlorine gas at the anode
  B) Hydrogen gas at the cathode and oxygen gas at the anode
  C) Sodium metal at the cathode and chlorine gas at the anode
  D) Sodium metal at the cathode and oxygen gas at the anode
  Show Answer
  The correct answer is A .
• Question 1650: The condition required for corrosion to take place is the presence of Options:
  A) Oxygen and Carbon (IV) oxide
  B) Water and Oxygen
  C) Water and Carbon (IV) oxide and Oxygen
  D) Water and Carbon (IV) oxide
  Show Answer
  The correct answer is B .