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Friday, 08 May 2026
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Chemistry Past Questions and Answers

Topic: Electrolysis

Jamb Chemistry Questions - Electrolysis

Question 16:
When a solution of silver (l) nitrate is saturated with hydrogen sulphide, a black precipitate forms which is?
  • A H<sub style='font-size: smaller;'>2</sub>S
  • B Ag<sub style='font-size: smaller;'>2</sub>S
  • C PbS
  • D HNO<sub style='font-size: smaller;'>3</sub>
  • E S
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Question 17:
A current of 10.0A was passed for 1 hour through a solution of copper (ll) sulphate between the copper electrodes. Which of the following observation would be correct?
(1 Faraday = 96,500 coulobms) (i) 0.186 mole of copper is dissolved from the anode. (ii) 0.372 mole of copper is deposited on the cathode. (iii) the original Cu2+ ion concentration of the solution remains unchanged. (iv) the original Cu2+ ion concentration of the solution decreases.
  • A I and ii
  • B I and iii
  • C I and iv
  • D Ii and iii
  • E Ii and iv
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Question 18:
Which of the following is NOT a redox reaction?
  • A 2HNO<sub style='font-size: smaller;'>2</sub> + 2HI → 2H<sub style='font-size: smaller;'>2</sub>O + 2NO + I<sub style='font-size: smaller;'>2</sub>
  • B Zn + H<sub style='font-size: smaller;'>2</sub>SO<sub style='font-size: smaller;'>4</sub> → ZnSO<sub style='font-size: smaller;'>4</sub> + H<sub style='font-size: smaller;'>2</sub>
  • C Ca(HCO<sub style='font-size: smaller;'>3</sub>)<sub style='font-size: smaller;'>2</sub> → CaCO<sub style='font-size: smaller;'>3</sub> + H<sub style='font-size: smaller;'>2</sub>O + CO<sub style='font-size: smaller;'>2</sub>
  • D 4FeO + O<sub style='font-size: smaller;'>2</sub> → 2Fe<sub style='font-size: smaller;'>2</sub>O<sub style='font-size: smaller;'>3</sub>
  • E 2Na + Cl<sub style='font-size: smaller;'>2</sub> → 2NaCl
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Question 19:
The colour imparted to a flame by calcuium ion is
  • A Green
  • B Blue
  • C Brick-red
  • D Yellow
  • E Lilac
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Question 20:
Some metals are extracted from their ores after some preliminary treatments by electrolysis (L), some of both processes (TL). Which set-up in the following for the extraction of ion, copper and aluminium is correct?
  • A Lron (L), copper (L) aluminium (T)
  • B Lron (T) copper (L) aluminium (T)
  • C Lron (TL) copper (TL) aluminium (TL)
  • D Iron (L) copper (T) aluminium (T)
  • E Lron (T) copper (L), aluminium (TL)
View Answer & Explanation