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 411: Which of the following is a physical change? Options:
  A) The bubbling of chlorine into water
  B) The bubbling of chlorine into a jar contanining hydrogen
  C) The dissolution of sodium chloride in water
  D) The passing of steam over heated iron
  Show Answer
  The correct answer is C .
• Question 412:

  

  Z in diagram above represents

  Options:
  A) heat of reaction
  B) activation energy
  C) free energy
  D) entropy of reaction
  Show Answer
  The correct answer is A .
• Question 413: In the discovery of protein, the instrument used is Options:
  A) cathode ray tube
  B) glass tube and discharge tube
  C) discharge tube with terminal cathode
  D) discharge tube with central cathode
  Show Answer
  The correct answer is D .
• Question 414:

  Which of the following are chemical changes?

  I. cooking of food
  II. digestion of food
  III. freezing of water
  IV. water is heated up

  Options:
  A) I and II
  B) I, II, and III
  C) III and IV
  D) all of the above
  Show Answer
  The correct answer is A .
• Question 415:

  Crude petroleum is converted to useful products by the processof?

  Options:
  A) fractional crystallization
  B) fractional distillation
  C) filtration
  D) chromatography
  Show Answer
  The correct answer is B .
• Question 416: The weakest attractive force that can be observed between two molecules is Options:
  A) ionic
  B) covalent
  C) co-ordinate covalent
  D) vander Waals
  Show Answer
  The correct answer is D .
• Question 417: 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 418: A rock sample was added to cold dilute HNO₃. The gas evolved was passed into a solution of acidified K₂Cr₂O₇ and the solution turned green. The sample contains Options:
  A) Cl^-
  B) NO₃^-
  C) SO₃^2-
  D) SO₄^2-
  Show Answer
  The correct answer is C .
• Question 419:

  Chromatography is used to separate components of mixture which differ in their rates of ?

  Options:
  A) diffusion
  B) migration
  C) reaction
  D) sedimentation
  Show Answer
  The correct answer is B .
• Question 420: An organic compound contains 60% carbon, 13.3% hydrogen and 26.7% oxygen. Calculate the empirical formula
  rn(C=12,H =1, O=16) Options:
  A) C ₅H ₁₂O
  B) C ₃H ₈O
  C) C ₆H ₁₃O ₂
  D) C ₄H ₉O
  Show Answer
  The correct answer is B .