Oxidation numbers and redox Quiz
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5 questions, one answer each
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1. What is the oxidation number of chromium in the dichromate(VI) ion, Cr₂O₇²⁻?
- A. +7
- B. +6
- C. +3
- D. +12
2. In which compound does oxygen have an oxidation number of −1?
- A. Na₂O₂
- B. Na₂O
- C. H₂O
- D. MgO
3. In the reaction Mg + Cl₂ → MgCl₂, what is the oxidising agent?
- A. Mg
- B. MgCl₂
- C. Cl₂
- D. Cl⁻
4. Which reaction is a disproportionation?
- A. Zn + Cu²⁺ → Zn²⁺ + Cu
- B. NaOH + HCl → NaCl + H₂O
- C. 2Mg + O₂ → 2MgO
- D. 2Cu⁺ → Cu + Cu²⁺
5. Which correctly describes MnO₄⁻ + 8H⁺ + 5e⁻ → Mn²⁺ + 4H₂O?
- A. Oxidation, as manganese goes from +7 to +2
- B. Reduction, as manganese goes from +7 to +2
- C. Reduction, as manganese goes from +2 to +7
- D. Oxidation, as electrons are gained