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 1541: What volume of 0.5 mol dm^-3 H₂SO₄ will exactly neutralize 20cm³ of 0.1 mol dm^-3 NaOH solution? Options:
  A) 2.0 cm³
  B) 5.0 cm³
  C) 6.8 cm³
  D) 8.3 cm³
  Show Answer
  The correct answer is A .
• Question 1542: CaO_s + H₂O_(l) → Ca(OH)_2(s) ΔH -65 kj. The process represented by the above equation is known as? Options:
  A) dissolution
  B) slaking
  C) liming
  D) mortaring
  Show Answer
  The correct answer is B .
• Question 1543: When plastics and packaging materials made from chloroethene are burnt in the open, the mixture of gases released into the atmosphere is most likely to contain? Options:
  A) ethane
  B) chlorine
  C) hydrogen chloride
  D) ethene
  Show Answer
  The correct answer is C .
• Question 1544: A carcinogenic substance is Options:
  A) asbestos dust
  B) sawdust
  C) nitrogen (II) oxide
  D) carbon (II) oxide
  Show Answer
  The correct answer is A .
• Question 1545:

  Two cylinders A and B each contains 30 cm³ of

  Oxygen and nitrogen respectively at the same temperature and pressure. If there are 5.0 moles of nitrogen, then the mass of oxygen is?

  Options:
  A) 3.2 g
  B) 6.4 g
  C) 80.0 g
  D) 160.0 g
  Show Answer
  The correct answer is D .
• Question 1546: Alkaonic acids have low volatility compared with alkanols because they? Options:
  A) are more polar than alkaonls
  B) have two oxygen atoms while alkanols have one
  C) form hydrogen bonds while alkanols do not
  D) form two hydrogen bonds while alkanols form one
  Show Answer
  The correct answer is D .
• Question 1547:

  An element, X, forms a volatile hydride XH₃ with a vapour density of 17.0. The relative atomic mass of X is?

  (H = 1)

  Options:
  A) 34.0
  B) 31.0
  C) 20.0
  D) 14.0
  Show Answer
  The correct answer is B .
• Question 1548: When sodium chloride and metallic sodium are each dissolved in water Options:
  A) both processes are exothermic
  B) both processes are endothermic
  C) the dissolution of metallic sodium is endothermic
  D) the dissolution of metallic sodium is exothermic
  E) the dissolution of sodium chloride is explosive
  Show Answer
  The correct answer is D .
• Question 1549:

  The solubility of Na₃AsO₄(H₂O)₁₂ is 38.9g per 100g H₂O. What is the mass percentage of Na₃AsO₄ in the saturated solution?

  (As = 75, Na = 23, O = 16, H = 1)

  Options:
  A) 87.27%
  B) 38.9%
  C) 19.1%
  D) 13.7%
  Show Answer
  The correct answer is C .
• Question 1550: The noble gases owe their inactivity to Options:
  A) Octet configuration
  B) Cyclic shape
  C) Hexagonal shape
  D) Obtuse configuration
  Show Answer
  The correct answer is A .