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Thursday, 11 June 2026
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Chemistry Past Questions and Answers

Chemistry Questions

Question 2816:
WAEC 2004
The reaction that takes place at the cathode when an aqueous solution of NaCI is electrolysed using carbon electrodes is
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  • A 2H<sup style='font-size: smaller;'>+</sup><sub style='font-size: smaller;'>2(g)</sub> + 2e<sup style='font-size: smaller;'>-</sup> → H<sub style='font-size: smaller;'>2(g)</sub>
  • B Na<sup style='font-size: smaller;'>+</sup><sub style='font-size: smaller;'>2(g)</sub> + e<sup style='font-size: smaller;'>-</sup> → Na<sub style='font-size: smaller;'>(s)</sub>
  • C 4OH<sup style='font-size: smaller;'>-</sup> → 2H<sub style='font-size: smaller;'>2</sub>O<sub style='font-size: smaller;'>(l)</sub> + O<sub style='font-size: smaller;'>2(g)</sub> +4e<sub style='font-size: smaller;'>-</sub>
  • D 2CI<sub style='font-size: smaller;'>-</sub> → CI<sub style='font-size: smaller;'>2(g)</sub> + 2e<sup style='font-size: smaller;'>-</sup>
View Answer & Explanation
Question 2817:
WAEC 2004
What of the following pairs of acid and base will produce a solution with pH less than 7 at equivalence point?
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  • A HNO<sub style='font-size: smaller;'>3</sub> and NaOH
  • B H<sub style='font-size: smaller;'>2</sub>SO<sub style='font-size: smaller;'>4</sub> and KOH
  • C HCI and Mg(OH) <sub style='font-size: smaller;'>2</sub>
  • D HNO <sub style='font-size: smaller;'>3</sub> and KOH
View Answer & Explanation
Question 2818:
WAEC 2004
WHICH OF THE FOLLOWING SALTS IS READILY SOLUBLE IN WATER?
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  • A PbCI<sub style='font-size: smaller;'>2</sub>
  • B Pb(NO <sub style='font-size: smaller;'>3</sub>) <sub style='font-size: smaller;'>2</sub>
  • C PbSO<sub style='font-size: smaller;'>4</sub>
  • D PbCO <sub style='font-size: smaller;'>3</sub>
View Answer & Explanation
Question 2819:
WAEC 2004
Which of the following factors that affect the rate of chemical reactions can be explained in terms of the collision theory? l. concentration ll. pressure lll. temperature lV catalyst
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  • A L and ll only
  • B L, ll and lll only
  • C L and lll only
  • D L, lll and IV only
View Answer & Explanation
Question 2820:
WAEC 2004
An orange drink concentrate is suspected to contain traces of poisonous green dye and a harmless dye having the same boiling point. Which of the following techniques is most suitable for isolating the dyes?
SchoolNGR Classroom
  • A Fractional distillation
  • B Paper chromatography
  • C Coagulation
  • D Recrystallization
View Answer & Explanation

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