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 831: How many moles HCL will be required to react with potassium heptaoxodichromate (VI) to produce 3 moles of chlorine? Options:
  A) 14
  B) 12
  C) 11
  D) 10
  Show Answer
  The correct answer is A .
• Question 832: A piece of burning sulphur will continue to burn in a gas jar of oxygen to give misty fumes which readily dissolved in water. The resulting liquid is Options:
  A) sulphur (VI) trioxide
  B) tetraoxosulphate (VI) acid
  C) trioxosulphate (IV) acid
  D) dioxosulphate (II) acid
  E) hydrogen sulphide
  Show Answer
  The correct answer is C .
• Question 833: An element wil readily form an electrovalent compound if it electron configuration is Options:
  A) 2, 8, 1
  B) 2, 8, 4
  C) 2, 8, 8
  D) 2, 8, 5
  Show Answer
  The correct answer is A .
• Question 834:

  10.0 dm³ of air containing H₂S as an impurity was passed through a solution of Pb(NO₃)₂ until all the H₂S had reacted. The precipitate of PbS was found to weigh 5.02 g. According to the equation: Pb(NO₃)₂ + H₂S → PbS + 2HNO₃ the percentage by volume of hydrogen sulphide in the air is?

  (Pb = 207, S = 32, GMV at s.t.p = 22.4dm³)

  Options:
  A) 50.2
  B) 47.0
  C) 4.70
  D) 0.47
  Show Answer
  The correct answer is C .
• Question 835:

  

  In the diagram above, mixture Y is

  Options:
  A) NH₄NO_3(s) + CaSO_4(s),/sub>
  B) NH₄CL_(s) + NaNO_2(s)
  C) NH₄NO_2(s) + Na₂SO_4(s)
  D) NH₄CL_(s) + Ca(OH)_2(s)
  Show Answer
  The correct answer is D .
• Question 836: A certain liquid has a high boiling point. It is viscous, non-toxic, miscible with water being very hygroscopic. This liquid is most likely to be? Options:
  A) CH₃CH₂CH₂HO
  B) CH₃CHOHCH₃
  C) CH₃CH₂CHOHCH₃
  D) CH₂OHCHOHCH₂OH
  Show Answer
  The correct answer is D .
• Question 837: Hypochlorous acid is used as a bleach because Options:
  A) it is a strong acid
  B) it yields chlorine readily in pure water
  C) it is an oxidising agent
  D) it is a weak acid
  E) it is a reducing agent
  Show Answer
  The correct answer is C .
• Question 838: Aromatic and aliphatic hydrocarbons can be distinguished from each other by the? Options:
  A) action of bromine
  B) use of polymerization reaction
  C) action of heat
  D) use of oxidation reaction
  Show Answer
  The correct answer is C .
• Question 839: The fraction of crude oil used as jet fuel is? Options:
  A) refinery gas
  B) diesel oil
  C) kerosene
  D) gasoline
  Show Answer
  The correct answer is C .
• Question 840:

  If 1 litre of 2.2M sulphuric acid is poured into a bucket containing 10 litre of water,and resulting solution mixed thoroughly, the resulting sulpuric acid concentration will be?

  Options:
  A) 2.2 M
  B) 1.1 M
  C) O.22 M
  D) 0. 11 M
  E) 0.20 M
  Show Answer
  The correct answer is C .