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 211:

  A compound contains 31.91% potassium, 28.93% chlorine and the rest oxygen. What is the chemical formula of the compound?

  [K = 39, Cl = 35.5, O = 16]

  Options:
  A) KClO₄
  B) KClO
  C) KClO₂
  D) KClO₃
  Show Answer
  The correct answer is D .
• Question 212: The solubility product of Cu(IO₃)₂ is 1.08 * 10^-7. Assuming that neither ions react appreciable with water to form H⁺ and OH^-, what is the solubility of this salt? Options:
  A) 2.7 * 10^-8 mol dm^-3
  B) 9.0 * 10^-8 mol dm^-3
  C) 3.0 * 10^-3 mol dm^-3
  D) 9.0 * 10^-3 mol dm^-3
  Show Answer
  The correct answer is D .
• Question 213: When 50cm³ of a saturated solution of sugar (molar mass 342.0g) at 40^oC was evaporated to dryness, 34.2g of dry solid was obtained. The solubility of sugar at 40^oC is Options:
  A) 10.0 moles dm^-3
  B) 7.0 moles dm^-3
  C) 3.5 moles dm^-3
  D) 2.0 moles dm^-3
  Show Answer
  The correct answer is D .
• Question 214: Which of the following compounds is the best possible anti-knock agent for petrol? Options:
  A) (CH₃)₂CH - CH(CH₃)CH₂CH₃
  B) CH₃CH₂(CH₃)CHCH₂CH₂CH₃
  C) CH₃CH₂(CH₃)CHCH₂CH₂CH₃
  D) (CH₃)₃C - CH₂CH₂CH₃
  Show Answer
  The correct answer is A .
• Question 215:

  

  In the diagram above, the purpose of the asbestos to

  Options:
  A) absorb impurities
  B) catalyze the reaction
  C) solidify the gas
  D) dry the gas
  Show Answer
  The correct answer is B .
• Question 216: When sodium hydroxide is heated with ammonium tetraoxosulphate (IV), the gas given off may be collected by? Options:
  A) bubbling it through concentrated H₂SO₂
  B) bubbling it through water and then passing it through calcium oxide
  C) passing it directly through calcium oxide
  D) passing it directly through calcium chloride
  Show Answer
  The correct answer is C .
• Question 217: The most common ores of iron include Options:
  A) haematite, malachite and limonite
  B) chalcolite, calamine and bornite
  C) magnetite, haematite and bornite
  D) magnetite, chalcolite and bornite
  Show Answer
  The correct answer is C .
• Question 218:

  What happens when alkanoic acids react with alcohols in the presence of an acid catalyst?

  Options:
  A) Saponification
  B) Esterification
  C) Polymerization
  D) Hydrolysis
  Show Answer
  The correct answer is B .
• Question 219:

  

  In the diagram above the activation energy is represented by

  Options:
  A) y - x
  B) x
  C) x - z
  D) y
  Show Answer
  The correct answer is A .
• Question 220: What volume of carbon (ll) oxide is produced by reacting excess carbon with 10 dm³ of oxygen? Options:
  A) 5 dm ³
  B) 20 dm ³
  C) 15 dm ³
  D) 10 dm ³
  Show Answer
  The correct answer is B .