Search SchoolNGR

Thursday, 18 June 2026
Register . Login

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 256:
A difference between chemical and physical change is that in a chemical change
  • A Oxygen is consumed
  • B Heat is supplied
  • C A reversible process oocurs
  • D A new substance is formed
View Answer & Explanation
Question 257:
The order in which a mixture of sand, ammonium chloride and sodium chloride can be separated is
  • A Dissolution → dryness → filtration → evaporation
  • B Filtration → sublimation → evaporation → dryness
  • C Sublimation → dissolution → filtration → evaporation
  • D Dissolution → filtration → sublimation → evaporation
View Answer & Explanation
Question 258:
Na2CO3(g) + 2HCl(aq) → 2NaCl(aq) + H2O(l) + CO2(g)
How many moles of sodium trioxocarbonate (IV) are there in a 25 cm3 solution which required 10cm3 of 0.05 mol dm-3 hydrochloric acid solution to neutralize it?
  • A 1.000 mole
  • B 0.100 mole
  • C 0.010 mole`
  • D 0.111 mole
View Answer & Explanation
Question 259:
In the diagram above, mixture Y is
  • A NH<sub style='font-size: smaller;'>4</sub>NO<sub style='font-size: smaller;'>3(s)</sub> + CaSO<sub style='font-size: smaller;'>4(s),/sub></sub>
  • B NH<sub style='font-size: smaller;'>4</sub>CL<sub style='font-size: smaller;'>(s)</sub> + NaNO<sub style='font-size: smaller;'>2(s)</sub>
  • C NH<sub style='font-size: smaller;'>4</sub>NO<sub style='font-size: smaller;'>2(s)</sub> + Na<sub style='font-size: smaller;'>2</sub>SO<sub style='font-size: smaller;'>4(s)</sub>
  • D NH<sub style='font-size: smaller;'>4</sub>CL<sub style='font-size: smaller;'>(s)</sub> + Ca(OH)<sub style='font-size: smaller;'>2(s)</sub>
View Answer & Explanation
Question 260:
What happens when zinc rod is immersed in copper (II) tetraoxosulphate (VI) solution/
  • A The blue colour of the solution disappears
  • B Electrons flow from copper to zinc
  • C The zinc rod remain undissolved
  • D The copper generate more copper ions
View Answer & Explanation