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 1881: 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 1882: Which group of elements forms hydrides that are pyramidal in structure? Options:
  A) III
  B) IV
  C) V
  D) VI
  Show Answer
  The correct answer is C .
• Question 1883: The products of the combustion of candle wax are Options:
  A) hydrogen and water
  B) oxygen and water
  C) carbon (IV) oxide and water
  D) carbon (II) oxide and water
  Show Answer
  The correct answer is C .
• Question 1884:

  What is the maximum number of electrons that can occupy the second energy level (n=2)?

  Options:
  A) 2 electrons
  B) 18 electrons
  C) 8 electrons
  D) 32 electrons
  Show Answer
  The correct answer is C .
• Question 1885: The following arrangement of elements in order of decreasing number of outer electrons; One of the elements is wrongly placed. Which is it? ALUMINIUM, CHLORINE, SILICON, MAGNESIUM AND SODIUM. Options:
  A) chlorine
  B) aluminium
  C) silicon
  D) magnesium
  E) sodium
  Show Answer
  The correct answer is B .
• Question 1886: The solubility curve shows the variation of solute concentration with Options:
  A) volume
  B) temperature
  C) vapour density
  D) pressure
  Show Answer
  The correct answer is B .
• Question 1887:

  What is the symbol used to represent an alpha particle?

  Options:
  A) α
  B) γ
  C) δ
  D) β
  Show Answer
  The correct answer is A .
• Question 1888: The brown fumes given off when trioxonitrate (V) acid is heated consist of ? Options:
  A) NO₂ and O₂
  B) H₂O and NO₂
  C) NO_2' O₂ and H₂O
  D) NO, NO₂ and H₂O
  Show Answer
  The correct answer is C .
• Question 1889:

  A current of 10.0A was passed for 1 hour through a solution of copper (ll) sulphate between the copper electrodes. Which of the following observation would be correct?

  (1 Faraday = 96,500 coulobms) (i) 0.186 mole of copper is dissolved from the anode. (ii) 0.372 mole of copper is deposited on the cathode. (iii) the original Cu²⁺ ion concentration of the solution remains unchanged. (iv) the original Cu²⁺ ion concentration of the solution decreases.

  Options:
  A) i and ii
  B) i and iii
  C) i and iv
  D) ii and iii
  E) ii and iv
  Show Answer
  The correct answer is B .
• Question 1890:

  Sodium sulphate decahydrate (Na₂SO₄.10 H₂O) on exposure to air loses all its water of crystallization.

  The process of loss is known as

  Options:
  A) efflorescence
  B) hygroscopy
  C) deliquescence
  D) effervescence
  E) dehydration
  Show Answer
  The correct answer is A .