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Tuesday, 16 June 2026
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Chemistry Past Questions and Answers

Topic: Separation of mixtures and purification of chemical substances

Jamb Chemistry Questions - Separation of mixtures and purification of chemical substances

Question 76:
A piece of sea shell, when dropped into a dilute solution of hydrochloric acid, produces a colourless, odourless gas which turns clear limewater milky. The sea shell contains
  • A Sodium chloride
  • B Ammonium nitrate
  • C Calcium carbonate
  • D Calcium chloride
  • E Magnesium chloride
View Answer & Explanation
Question 77:
An aqueous solution of a metal salt, M, gives a white precipitate with NaOH which dissolves in excess NaOH. With aqueous ammonia, the solution of M also gives a white precipitate which dissolves in excess ammonia. Therefore cartion in M is
  • A Zn <sup style='font-size: smaller;'>++</sup>
  • B Ca<sup style='font-size: smaller;'>++</sup>
  • C Ai<sup style='font-size: smaller;'>+++</sup>
  • D Pb<sup style='font-size: smaller;'>++</sup>
  • E Cu<sup style='font-size: smaller;'>++</sup>
View Answer & Explanation
Question 78:
Which of the following metals will displace iron from a solution of iron(ll)tetraoxosulphate(lV)?
  • A Copper
  • B Mercury
  • C Silver
  • D Zinc
  • E Gold
View Answer & Explanation
Question 79:
A man suspected of being drunk is made to pass his breath into acidified potassium dichlormate solution. If his breath carries a significant level of ethanol, the final colour of the solution is?
  • A Pink
  • B Purple
  • C Orange
  • D Blue-black
  • E Green
View Answer & Explanation
Question 80:
An organic compound decolourized acidified KMnO4 solution but failed to react with ammoniacal silver nitrate solution. The organic compound is likely to be?
  • A A carbonxylic acid
  • B An alkane
  • C An alkene
  • D An alkyne
  • E An akanone
View Answer & Explanation