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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 126:
Which of the following is a physical change?
  • 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
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Question 127:
Which of the following compounds gives a yellow residue when heated and also reacts with aqueous sodium hydroxide to give a white gelatinous precipitate soluble in excess sodium hydroxide solution?
  • A (NH<sub style='font-size: smaller;'>4</sub>)CO<sub style='font-size: smaller;'>3</sub>
  • B ZnCO<sub style='font-size: smaller;'>3</sub>
  • C Al<sub style='font-size: smaller;'>2</sub>(SO<sub style='font-size: smaller;'>4</sub>)<sub style='font-size: smaller;'>3</sub>
  • D PbCO[sub][/sub]3
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Question 128:
A cycloalkane with the molecular formula C5H10 has ?
  • A One isomer
  • B Two isomers
  • C Three isomers
  • D Four isomers
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Question 129:
Alkaonic acids have low volatility compared with alkanols because they?
  • A Are more polar than alkaonls
  • B Have two oxygen atoms while alkanols have one
  • C Form hydrogen bonds while alkanols do not
  • D Form two hydrogen bonds while alkanols form one
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Question 130:
The octane number of a fuel whose performance is the same as that of a mixture of 55 g of 2,2,4- trimethly pentane and 45 g of n-heptane is ?
  • A 45
  • B 55
  • C 80
  • D 100
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