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 471: The products of the reaction between dilute sulphuric acid and sodium thiosulphate crystals are? Options:
  A) Na₂SO₄ + SO₂ + O₂ + H₂O
  B) Na₂SO₃ + SO₃ + O₂ + H₂O
  C) Na₂SO₄ + SO₂ + S + H₂O
  D) Na₂SO₄ + SO₃ + S + H₂O
  E) Na₂SO₄ + SO₂ + H₂O only
  Show Answer
  The correct answer is C .
• Question 472: Na₂C₂O₄ + CaCl₂ → CaC₂O₄ + 2NaCl. Given a solution of 1.9g of sodium oxalate in 50g of water at room temperature, calculate the minimum volume of 0.1 M calcium oxalate using the above equation? Options:
  A) 1.40 χ 10² dm³
  B) 14.0 χ 10² cm³
  C) 1.40 χ 10^-2 dm^-2
  D) 14.0 χ 10^-2 cm³
  Show Answer
  The correct answer is A .
• Question 473:

  The collision theory explains reaction rates in terms of

  Options:
  A) size of the product
  B) frequency of collision of the reactants
  C) size of reactant
  D) frequency of collision of the products
  Show Answer
  The correct answer is B .
• Question 474: Which of the following elements will form oxide which will dissolve both in dilute HNO₃ and NaOH solutions to form salts? Options:
  A) Al
  B) Mg
  C) Ag
  D) Mn
  Show Answer
  The correct answer is A .
• Question 475: The impurities formed during the laboratory preparation of chlorine gas are removed by Options:
  A) H₂O
  B) NH₃
  C) H₂SO₄
  D) HCl
  Show Answer
  The correct answer is A .
• Question 476: When air is passed through alkaline pyrogallol and then over quicklime, the only gases left are? Options:
  A) nitrogen and carbondoxide
  B) the rare gases
  C) nitrogen and oxygen
  D) nitrogen and the rare gases
  E) nitrogen, carbonioxide and the rare gases
  Show Answer
  The correct answer is D .
• Question 477: Which of the following pollutants is associated with brain damage? Options:
  A) Carbon (ll) oxide
  B) Radioactive fallout
  C) Biodegradable waste
  D) Sulphus (lV) oxide
  Show Answer
  The correct answer is A .
• Question 478: The method that can be used to convert hard water to soft water is Options:
  A) chlorination
  B) passage over activated charcoal
  C) the use of an ion-exchange resin
  D) aeration
  Show Answer
  The correct answer is C .
• Question 479: Stainless steel is an alloy of? Options:
  A) Iron, carbon and silver
  B) iron, carbon and lead
  C) iron, carbon and chromium
  D) iron and carbon only
  Show Answer
  The correct answer is C .
• Question 480:

  What is the concentration of a solution containing 2g of NaOH in 100cm³ of solution?
  [Na = 23, O = 16, H = 1]

  Options:
  A) 0.40 mol dm^-3
  B) 0.50 mol dm^-3
  C) 0.05 mol dm^-3
  D) 0.30 mol dm^-3
  Show Answer
  The correct answer is B .