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 631: Which of the following tests would confirm-unequivocally that a solution X contain the sulphate ion if it gives with Options:
  A) silver nitrates solution, a white precipates insoluble in dilute HNO₃
  B) barium chloride solution, a white precipitate insoluble in dilute H₂SO₄
  C) barium chloride solution, a white precipitate insoluble in dilute HCl
  D) barium chloride solution a white precipitate soluble in dilute ammonia
  E) barium chloride solution a white precipitate insoluble in dilute HCl
  Show Answer
  The correct answer is C .
• Question 632: Given that the molecular mass of iron is 56 and that of oxygen is 16, how many moles of iron(iii)oxide will be contained in 1kg of the compound? Options:
  A) 25.0 moles
  B) 12.5 moless
  C) 6.25 moles
  D) 3.125 moles
  E) 0.625 moles
  Show Answer
  The correct answer is C .
• Question 633: Which of the following derivatives of nitrogen affords an aqueous solution having a pH of less that 7? Options:
  A) N₂O
  B) NO
  C) NO₂
  D) NaNO₃
  E) NH₃
  Show Answer
  The correct answer is C .
• Question 634:

  

  In the above experiment, the litmus paper will initially

  Options:
  A) be bleached
  B) turn green
  C) turn red
  D) turn blue
  E) turn black
  Show Answer
  The correct answer is D .
• Question 635: Ethyne is passed through a hot tube containing organo-nickel catalyst to produce Options:
  A) isoprene
  B) polythene
  C) ethanol
  D) benzene
  Show Answer
  The correct answer is D .
• Question 636:

  

  The graph above demonstrate the effect of

  Options:
  A) surface area on the rate of reaction
  B) catalyst on the rate of reaction
  C) pressure on the rate reaction
  D) concentration on the rate of reaction
  Show Answer
  The correct answer is A .
• Question 637: Smog usually occurs over cities which Options:
  A) burn a lot of fossil fuels
  B) have very few plants
  C) are surrounded by water
  D) are overpopulated
  Show Answer
  The correct answer is A .
• Question 638: 3. 06 g of a sample of potassium trioxochlorate (V) (KCIO) was required to make a saturated solution with 10cm³ of water at 25^oC. The solubility of the salt at 25^oC is [K =39, Cl = 35.5, O = 16] Options:
  A) 5.0 moles dm³
  B) 3.0 moles dm³
  C) 2.5 moles dm³
  D) 1.0 molesv
  E) 0.5 moles dm³
  Show Answer
  The correct answer is C .
• Question 639: Sodium hydroxide solution can be conveniently stored in a container made of? Options:
  A) lead
  B) zinc
  C) aluminium
  D) copper
  Show Answer
  The correct answer is D .
• Question 640:

  Which of the following substances is NOT hygroscopic?

  Options:
  A) Salt
  B) Sugar
  C) Silica gel
  D) Aluminum
  Show Answer
  The correct answer is D .