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 21: Catalytic hydrogenation of benzene produces? Options:
  A) an aromatic hydrocarbon
  B) margarine
  C) cyclohexane
  D) D.D.T
  Show Answer
  The correct answer is C .
• Question 22: When 50cm² of a saturated solution of sugar of molar mass 342 g at 40^oC was evaporated to dryness, 34.2g of dry solid was obtained. The solubility of sugar at 40^oC is Options:
  A) 2.0 mol dm^-3
  B) 3.5 mol dm^-3
  C) 7.0 mol dm^-3
  D) 10.0 mol dm^-3
  Show Answer
  The correct answer is A .
• Question 23:

  What is eutrophication?

  Options:
  A) The release of harmful chemicals into water bodies
  B) The excessive growth of algae due to nutrient enrichment
  C) The presence of heavy metals in water
  D) The formation of oil slicks on water surfaces
  Show Answer
  The correct answer is B .
• Question 24: 50 cm³ of gas was collected over water at 10^oC and 765 mm Hg. Calculate the volume of the gas at s.t.p. if the saturated vapour pressure of water at 10 ^oC is 5mm Hg Options:
  A) 49.19 cm ³
  B) 48.87 cm ³
  C) 48.55 cm ³
  D) 48.23 cm ³
  Show Answer
  The correct answer is D .
• Question 25: Three drops of a 1.0 mol dm^-3 solution of HCl was added to 20 cm³ of a solution of pH6.4. The pH of the resulting solution will be Options:
  A) close to that of pure water
  B) less than 6.4
  C) greater than 6.4
  D) unaltered
  Show Answer
  The correct answer is B .
• Question 26: Methylethanoate reacts with ammonia to yield? Options:
  A) mettylamine and ethanol
  B) ethylamine and methanol
  C) methanamide and ethanol
  D) ethanamide and methanol
  Show Answer
  The correct answer is D .
• Question 27: PCL5(g)= PCL3(g) + Cl2(g)In the reaction above, a decrease in pressure will Options:
  A) Decelerate the reaction
  B) Increase yield of Pcl3
  C) Increase the yield of Pcl5
  D) Accurate the reaction
  Show Answer
  The correct answer is B .
• Question 28: Element X, Y and Z belong to a groups I, V and VII respectively. Which of the following is TRUE about the bond types of XZ and YZ₃? Options:
  A) Both are electrovalent
  B) Both are covalent
  C) XZ is electrovalent and YZ₃ is covalent
  D) XZ is covalent and YZ₃ is electrovalent
  Show Answer
  The correct answer is C .
• Question 29:

  

  The compound above is an

  Options:
  A) alkanone
  B) alkanoate
  C) alkanal
  D) akanol
  Show Answer
  The correct answer is A .
• Question 30: The compounds CH₃CH₂CHO and CH₃COCH₃ can be distinguished from each other using Options:
  A) Dilute ammonia
  B) Benedict's solution
  C) Tollen's reagent
  D) Sodium hydroxide solution
  Show Answer
  The correct answer is C .