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 141: A sample of hard water contains some calcium sulphate and calcium hydrogen carbonate. The total hardness may therefore be removed by Options:
  A) boiling the water
  B) adding excess calcium hydroxide
  C) adding a calculated amount of calcium hydroxide
  D) adding sodium carbonate
  E) adding magnesium hydroxide
  Show Answer
  The correct answer is D .
• Question 142:

  

  Figure 1 above shows part of the periodic Table which of the elements belongs to the p-block?

  Options:
  A) S, T and U
  B) V, W and X
  C) S and T only
  D) P, Q and R
  E) V, W, X and S
  Show Answer
  The correct answer is D .
• Question 143:

  Calculate the volume in cm³ of oxygen evolved at s.t.p when a current of 5A is passed through acidified water for 193s?

  [F = 96500 C mol¹. Molar volume of a gas at s.t.p = 22.4dm³]

  Options:
  A) 0.056dm³
  B) 0.224dm³
  C) 224.000dm³
  D) 56.000dm³
  Show Answer
  The correct answer is A .
• Question 144:

  0.1 faraday of electricity deposited 2.95 g of nickel during electrolysis of an aqueous solution.

  Calculate the number of moles of nickel that will be deposited by 0.4 faraday? (Ni = 58.7)

  Options:
  A) 0.20
  B) 0.30
  C) 0.04
  D) 5.87
  Show Answer
  The correct answer is A .
• Question 145: 50 cm³ of gas was collected over water at 10^oC and 765 mm Hg. Calculate the volume of the gas at s.t.p. if the saturated vapour pressure of water at 10 ^oC is 5mm Hg Options:
  A) 49.19 cm ³
  B) 48.87 cm ³
  C) 48.55 cm ³
  D) 48.23 cm ³
  Show Answer
  The correct answer is D .
• Question 146: Which of the following processes NOT lead to a chemical change? Options:
  A) Strirring iron in sulphur (IV) acid
  B) Stirring sodium carbonate in water
  C) Stirring glucose in concentrated sulphur (IV) acid
  D) Mixing sulphur (IV) acid with potassium carbonate
  E) Titrating an acid against base
  Show Answer
  The correct answer is B .
• Question 147:

  Sodium reacts vigorously with water to produce

  Options:
  A) Sodium chloride (NaCl) and oxygen gas (O2)
  B) Sodium nitrate (NaNO3) and water (H2O)
  C) Sodium hydroxide (NaOH) and hydrogen gas (H2)
  D) Sodium oxide (Na2O) and hydrogen gas (H2)
  Show Answer
  The correct answer is C .
• Question 148: In the preparation of carbon monoxide by heating ethanedioic acid with concentrated sulphuric acid, the concentrated sulphuric acid act as? Options:
  A) an oxidizing agent
  B) a reducing agent
  C) a dehydrating agent
  D) a reaction medium
  E) a catalyst
  Show Answer
  The correct answer is C .
• Question 149:

  C₂H₅OH_(aq) → Y

  If the above reaction takes place in conc. H₂SO₄ at 180^o, Y represents

  Options:
  A) CH₄
  B) C₂H₅COOH
  C) C₂H₄
  D) CH₃OCH₃
  Show Answer
  The correct answer is C .
• Question 150: The thermal decomposition of copper (ll)trioxonitrate (V) yields copper (ll) oxide, oxygen and? Options:
  A) nitrogen (ll) oxide
  B) nitrogen (l) oxide
  C) nitrogen (lV) oxide
  D) nitrogen
  Show Answer
  The correct answer is C .