REDOX Reactions Practice Questions PDF

1. What is the formula of the dichromate(VI) ion? * A) CrO42- * B) Cr2O72- * C) Cr3+ * D) CrO3- 2. What is the colour of the dichromate(VI) ion in aqueous solution? * A) Green * B) Orange * C) Purple * D) Colourless 3. What is the formula of the manganate(VII) ion? * A) Mn2+ * B) MnO4- * C) MnO42-...

1. What is the formula of the dichromate(VI) ion? * A) CrO42- * B) Cr2O72- * C) Cr3+ * D) CrO3- 2. What is the colour of the dichromate(VI) ion in aqueous solution? * A) Green * B) Orange * C) Purple * D) Colourless 3. What is the formula of the manganate(VII) ion? * A) Mn2+ * B) MnO4- * C) MnO42- * D) MnO2 4. What is the colour of the manganate(VII) ion in aqueous solution? * A) Green * B) Orange * C) Purple * D) Colourless 5. In the reduction of dichromate(VI), what is the product ion formed? * A) Cr2O72- * B) CrO42- * C) Cr3+ * D) Cr2+ 6. What is the colour of the Cr3+ ion in aqueous solution? * A) Green * B) Orange * C) Purple * D) Colourless 7. In the reduction of manganate(VII) in acidic conditions, what is the main product? * A) MnO2 * B) Mn2+ * C) Mn3+ * D) MnO42- 8. What is the colour of the Mn2+ ion in aqueous solution? * A) Green * B) Orange * C) Purple * D) Colourless 9. What is the formula of the thiosulfate ion? * A) SO42- * B) SO32- * C) S2O32- * D) S4O62- 10. What is the formula of the tetrathionate ion, formed from the oxidation of thiosulfate? * A) SO42- * B) SO32- * C) S2O32- * D) S4O62- 11. What is the formula of the oxalate ion? * A) CO32- * B) C2O42- * C) HCO3- * D) CH3COO- 12. When oxalate is oxidised, what is the gaseous product formed? * A) O2 * B) CO * C) CO2 * D) H2 13. What is the oxidation state change of iron in the reaction: Fe2+ -> Fe3+ + e- ? * A) +2 to +3 * B) +3 to +2 * C) 0 to +2 * D) +2 to 0 14. During a manganate(VII) titration with Fe2+, what colour change is observed at the endpoint? * A) Purple to colourless * B) Colourless to purple * C) Orange to green * D) Green to orange 15. In iodometry, what is the colour of starch indicator in the presence of iodine (I2)? * A) Colourless * B) Yellow * C) Blue/black * D) Orange Answers and Explanations: 1. B) Cr2O72- - This is the correct formula for dichromate(VI). 2. B) Orange - Dichromate(VI) is orange in solution. 3. B) MnO4- - This is the correct formula for manganate(VII). 4. C) Purple - Manganate(VII) is purple in solution. 5. C) Cr3+ - This is the product of the reduction in acidic conditions. 6. A) Green - Cr3+ ions are green in solution. 7. B) Mn2+ - This is the main product in acidic conditions. 8. D) Colourless - Mn2+ ions are very pale pink, often considered colourless. 9. C) S2O32- - This is the correct formula. 10. D) S4O62- - This is the tetrathionate ion. 11. B) C2O42- - This is the correct formula. 12. C) CO2 - Carbon dioxide is formed. 13. A) +2 to +3 - Iron(II) is oxidised to iron(III). 14. B) Colourless to purple - The rst slight excess of MnO4- gives a permanent purple colour. 15. C) Blue/black - Starch forms a characteristic blue/black complex with iodine. Powered by pmfm.ai Request Support fi