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 601: A compound contains 40.0% C, 6.7% H 53.3% O. If the molecular mass of the compound is 180, its molecular formula is [C =12, H =1,O] Options:
  A) CH₂O
  B) C₃H₆O₃
  C) C₆H₆O₃
  D) C₆H₁₂O₆
  Show Answer
  The correct answer is D .
• Question 602: The reddish–brown rust on ion roofing sheets consists of Options:
  A) Fe³ + (H₂O)₆
  B) FeO.H₂O
  C) Fe₂O₃.3H₂O
  D) Fe₃O₄.2H2₂O
  Show Answer
  The correct answer is C .
• Question 603:

  The molar ratio of carbon to hydrogen of a volatile liquid compound is 1: 2. 0. 12 g of the liquid on evaporation at s.t.p. gave 32 cm³ of vapour. The molecular formula of the liquid is

  [G.M.V =22.4 dm ³, C = 12, H = 1]

  Options:
  A) C ₃ H ₆
  B) C ₄H ₈
  C) C ₅C ₁₀
  D) C ₆H ₁₂
  Show Answer
  The correct answer is D .
• Question 604: The constituent of air necessary in the rusting process are Options:
  A) O₂ and H₂O
  B) Ar and CO₂
  C) CO₂ and H₂O
  D) O₂ and CO₂
  Show Answer
  The correct answer is D .
• Question 605:

  Liquid black soap is made by boiling palm oil with liquid extract of ash. The function of the ash is to provide the

  Options:
  A) Acid
  B) Ester of alkanoic acid
  C) Alkali
  D) Alkanol
  Show Answer
  The correct answer is C .
• Question 606: An element used in the production of matches is Options:
  A) nitrogen
  B) aluminium
  C) copper
  D) sulphur
  Show Answer
  The correct answer is D .
• Question 607: The principle of column chromatography is based on the ability of the constituents to Options:
  A) move at different speeds in the column
  B) dissolve in each other in the column
  C) react with the solvent in the column
  D) react with each other in the column
  Show Answer
  The correct answer is A .
• Question 608:

  2KClO3(g) MNO3→ 2KCl(s) + 3O2(g)

  The importance of the catalyst in the reaction above is that

  Options:
  A) heating may not be required before the reaction takes place
  B) the reaction is controllable even at a high temperature
  C) the reaction produces large quantity of oxygen
  D) the reaction takes place more rapidly at a lower temperature
  Show Answer
  The correct answer is D .
• Question 609: The pair of organic compounds that are isomers is Options:
  A) Benzene and methylbenzene
  B) Trichloromethane and tetrachloromethane
  C) Ethanol and propane
  D) But-1-ene and but-2-ene
  Show Answer
  The correct answer is D .
• Question 610: Water for town supply is chlorinate to make it free from Options:
  A) bad colour
  B) bacteria
  C) temporary hardness
  D) permanent hardness
  Show Answer
  The correct answer is B .