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Wednesday, 17 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 176:
Oxygen is a mixture of two isotopes 16-O and 18-O with relative abundances of 90% and 10% respectively. The relative atomic mass of oxygen is?
  • A 16.0
  • B 16.2
  • C 17.0
  • D 18.0
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Question 177:
On recrystallization, 20g of magnesium tetraoxosuphate (IV) forms 41 g of magnesium tetraoxosulphate (IV) crystals, MgSO4. yH2O. The value of y is?
(Mg = 24, S = 32, O = 16, H = 1)
  • A 1
  • B 3
  • C 5
  • D 7
View Answer & Explanation
Question 178:
Which of the aqueous solutions with the pH values below will liberate hydrogen when it react with magnesium metals?
  • A 13.0
  • B 7.0
  • C 6.5
  • D 3.0
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Question 179:
Given that 15.00 cm3 of H2
SO4 was required to completely neutralize 25.00 cm3 of 0.125 mol dm-3 NaOH, calculate the molar concentration of the acid solution:
  • A 0.925 mol dm<sup style='font-size: smaller;'>-3</sup>
  • B 0.156mol dm<sup style='font-size: smaller;'>-3</sup>
  • C 0.104 mol dm<sup style='font-size: smaller;'>-3</sup>
  • D 0.023 mol dm<sup style='font-size: smaller;'>-3</sup>
View Answer & Explanation
Question 180:
A sample of a substance containing only C and H burns in excess O2 to yield 4.4g of CO2
and 2.7 g of H2O. The empirical formula of a substance is?
(C = 12, O = 16, H = 1)
  • A CH<sub style='font-size: smaller;'>3</sub>
  • B CH<sub style='font-size: smaller;'>2</sub>
  • C CH<sub style='font-size: smaller;'>4</sub>
  • D C<sub style='font-size: smaller;'>2</sub>H<sub style='font-size: smaller;'>24</sub>
View Answer & Explanation