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 481: Coal gas is made up of carbon (II) oxide, hydrogen and? Options:
  A) nitrogen
  B) air
  C) argon
  D) methane
  Show Answer
  The correct answer is D .
• Question 482: An efflorescent compound is a substance that? Options:
  A) absorbs water froom the air without dissolving in it
  B) is capable of giving off coloured luminosity
  C) gives out water to the atmosphere
  D) absorbs water from the air and dissolves in it
  E) gives out its water of crystallization on heating
  Show Answer
  The correct answer is C .
• Question 483: The reaction of zinc with copper (ll) ions in aqueous solution can be represented as follows: Cu ²⁺(aq) +Zn (s) → Cu(s) + Zn ²⁺(aq).Which of the following is the most complete description of this reaction? Options:
  A) Cpper (ll) ions are being reduced
  B) Zinc is being oxidized.
  C) Copper (ll) ions and zinc are being reduced
  D) copper (ll) ions and zinc are being oxidized
  E) copper(ll) ions are being reduced and zinc oxidized
  Show Answer
  The correct answer is E .
• Question 484: In the extraction of iron in the blast furnace, limestone is used to? Options:
  A) release CO₂ for the reaction
  B) reduce the iron ore
  C) increase the strenght of the iron
  D) remove impurities
  Show Answer
  The correct answer is D .
• Question 485:

  A certain hydrocarbon on complete combustion at s.t.p produced 89.6dm${}^3$ of CO${}_2$ and 54g of water. The hydrocarbon should be

  Options:
  A) C${}_6$H${}_6$
  B) C${}_4$H${}_{10}$
  C) C${}_5$H${}_{10}$
  D) C${}_4$H${}_6$
  Show Answer
  The correct answer is D .
• Question 486: It is difficult to achieve an orderly arrangement of the molecules of a gas because they Options:
  A) have no definite shape
  B) have little force of attraction between them
  C) can collide with one another in the container
  D) are too small in size
  Show Answer
  The correct answer is B .
• Question 487: Which of the following types of reactions takes place between C₂H₄ and the halogens? Options:
  A) Substitution
  B) Polymerization
  C) Addition
  D) Saponification
  E) Oxidation
  Show Answer
  The correct answer is C .
• Question 488:

  A given volume of methane diffuses in 20s. How long will it take the same volume of sulphur (IV) oxide to diffuse under the same conditions?

  [C = 12, H = 1, S = 32, O = 16].

  Options:
  A) 5s
  B) 20s
  C) 40s
  D) 60s
  Show Answer
  The correct answer is C .
• Question 489: Alloys are best prepared by? Options:
  A) high temperature weilding of the metals
  B) electrolysis using the major metallic component as cathode
  C) reducing a mixture of the oxies of the elements
  D) cooling a molten mixture of the necessary elements
  Show Answer
  The correct answer is D .
• Question 490: The correct order of increasing boiling points of the following compounds C₃H₇OH, C₇H₁₆ and C₄H₁₀ is Options:
  A) C₃H₇OH → C₄H₁₀ → C₇H₁₀
  B) C₄H₁₀ → C₇H₁₆ → C₃H₇OH
  C) C₇H₁₆ → C₃H₇OH → C₄H₁₀
  D) C₄H₁₀ → C₃H₇OH → C₇H₁₆
  Show Answer
  The correct answer is D .