Redox Quiz
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5 questions, one answer each
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1. Which statement correctly defines oxidation in terms of electrons?
- A. Oxidation is the loss of electrons or an increase in oxidation number
- B. Oxidation is the gain of electrons or a decrease in oxidation number
- C. Oxidation is the loss of oxygen atoms from a compound
- D. Oxidation is the gain of oxygen atoms in a compound
2. In the reaction 2Cu + O₂ → 2CuO, what is the oxidation number of copper in CuO?
- A. +1
- B. +2
- C. +3
- D. 0
3. Consider the reaction: Zn + Cu²⁺ → Zn²⁺ + Cu. Which statement is correct?
- A. Zinc is the oxidising agent because it gains electrons
- B. Copper ions are the reducing agent because they are reduced
- C. Zinc is the reducing agent because it is oxidised and loses electrons
- D. Copper ions are the oxidising agent because they gain electrons
4. When potassium manganate(VII) is added to an aqueous solution containing iron(II) ions, the solution changes from purple to colourless. What does this colour change indicate?
- A. No redox reaction has occurred; the colour change is due to dilution
- B. A redox reaction has occurred; the manganate(VII) ions have been reduced
- C. Iron(II) ions have been oxidised to iron(III) ions only; no reduction has occurred
- D. Manganate(VII) ions have been oxidised to a colourless product
5. Analyse the reaction: 2KI + Cl₂ → 2KCl + I₂. Using oxidation numbers, which of the following correctly identifies the oxidation and reduction occurring?
- A. Iodine is oxidised from −1 to 0; chlorine is reduced from 0 to −1
- B. Iodine is oxidised from 0 to −1; chlorine is reduced from −1 to 0
- C. Iodine is reduced from 0 to +1; chlorine is oxidised from 0 to −1
- D. Chlorine is oxidised from 0 to −1; iodine is reduced from +1 to 0