Redox Practice Paper

© chiasamuel 2025 CANDIDATE NAME CLASS INDEX NUMBER Chpt 10: Oxidation and Reduction MOCK PAPER READ THESE INSTRUCTIONS FIRST Write your centre number, index number and name on all the work you hand in. You may use an HB pencil for any diagrams, graphs or rough working. Write in dark blue or black pen. Do not use staples, paper clips, glue or correction fluid. The use of an approved scientific calculator is expected, where appropriate. You may lose marks if you do not show your working or if you do not use appropriate units. DO NOT WRITE ON ANY BARCODES. FOR EXAMINERS’ USE

© chiasamuel 2025 1 What is the oxidation state of oxygen in hydrogen peroxide? A +1 B +2 C -1 D -2 2 4 students wrote statements about redox reactions. Anthony: When there is an increase of electrons, the substance gaining electrons is oxidised. Bryan: The oxidation state of hydrogen in Sodium Hydride is +1. Chris: For a redox reaction to occur, both oxidation and reductions must occur at the same time. Daniel: All redox reactions are neutralisation reactions. Which student is correct? A Anthony B Bryan C Chris D Daniel

© chiasamuel 2025 3 Aqueous potassium iodide and acidified potassium manganate(VII) were added separately to separate samples of hydrogen peroxide. The observations are summarised in the table. reagent added to hydrogen peroxide observations aqueous potassium iodide aqueous potassium iodide turns from colourless to brown acidified potassium manganate (VII) acidified potassium manganate (VII) turns from purple to colourless Which set of properties are correct? aqueous potassium iodide aqueous potassium manganate A oxidising agent reducing agent B oxidising agent oxidising agent C reducing agent oxidising agent D reducing agent reducing agent 4 Substance T is known to be a compound that has potassium cations. It is added into H ₂ O ₂ solution. Upon reaction, it is observed that the colour of T changes from purple to colourless. Which anion is present in substance T ? A MnO ₄⁺ B MnO ₄⁻ C I ⁺ D I ⁻

© chiasamuel 2025 5 Which of the following definitions of reduction is correct? Oxygen Hydrogen Electrons A Gain Lose Lose B Lose Gain Gain C Gain Gain Lose D Gain Lose Gain 6 Study the below chemical reaction. 2NH ₃ + 3CuO→N ₂ + 3Cu + 3H ₂ O (a) In terms of oxidation state, explain whether this reaction is a redox reaction. [3] (b) A test for the presence of reducing agents is using an oxidising agent [potassium (VII) manganate]. What is the observati