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CAIE IGCSE Chemistry Identifying Redox by Oxygen Transfer

CAIE IGCSE Chemistry Identifying Redox by Oxygen Transfer
Cambridge IGCSE Chemistry 0620 syllabus for exams in 2026, 2027 and 20282026–2028

Practise recognising a redox equation when one reactant gains oxygen while another loses oxygen, so oxidation and reduction occur together.

How this is tested

  • identify a redox equation by finding simultaneous oxygen gain and oxygen loss

Question 16

[Maximum number: 1]

Which equation represents a redox reaction?

A

AgNO3+NaCl→AgCl+NaNO3\mathrm{AgNO}_{3}+\mathrm{NaCl} \rightarrow \mathrm{AgCl}+\mathrm{NaNO}_{3}

B

PCl5+4H2O→H3PO4+5HCl\mathrm{PCl}_{5}+4 \mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{H}_{3} \mathrm{PO}_{4}+5 \mathrm{HCl}

C

3Fe+4H2O→Fe3O4+4H23 \mathrm{Fe}+4 \mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{Fe}_{3} \mathrm{O}_{4}+4 \mathrm{H}_{2}

D

MgCO3+2HCl→MgCl2+CO2+H2O\mathrm{MgCO}_{3}+2 \mathrm{HCl} \rightarrow \mathrm{MgCl}_{2}+\mathrm{CO}_{2}+\mathrm{H}_{2} \mathrm{O}