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CAIE IGCSE Chemistry 6.4.7 Reduction in Terms of a Gain of Questions

Identify reduction as electron gain, track reduced species in ionic equations and write balanced reduction half-equations.

Syllabus
2026–2028
Course
Chemistry 0620

Exam points

  • define reduction as gain of electrons or a decrease in oxidation number
  • identify the reduced species by finding the electron acceptor in an ionic equation
  • write a balanced reduction half-equation with gained electrons on the left
  • explain reduction of ions and elements using electron transfer

CAIE IGCSE Chemistry 6.4.7 Reduction in Terms of a Gain of Questions question 1

[Maximum number: 1]

Which of these reactions shows only reduction?

A

Cu2++2e−→Cu\mathrm{Cu}^{2+}+2 \mathrm{e}^{-} \rightarrow \mathrm{Cu}

B

Fe2O3+3CO→2Fe+3CO2\mathrm{Fe}_{2} \mathrm{O}_{3}+3 \mathrm{CO} \rightarrow 2 \mathrm{Fe}+3 \mathrm{CO}_{2}

C

HCl+NaOH→NaCl+H2O\mathrm{HCl}+\mathrm{NaOH} \rightarrow \mathrm{NaCl}+\mathrm{H}_{2} \mathrm{O}

D

Mg+ZnSO4→Zn+MgSO4\mathrm{Mg}+\mathrm{ZnSO}_{4} \rightarrow \mathrm{Zn}+\mathrm{MgSO}_{4}

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