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Redox
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Redox
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Which row correctly describes oxidation in terms of oxygen, electrons and oxidation state?
| oxygen is | electrons are | oxidation state is | |
| A | added | added | increased |
| B | added | lost | increased |
| C | lost | added | decreased |
| D | lost | lost | decreased |
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Magnesium reacts with iron(III) oxide in the following reaction.
magnesium + iron(III) oxide → magnesium oxide + iron
Which statement about this reaction is correct?
Magnesium oxide is reduced
Iron is oxidised
Magnesium is oxidised
Iron(III) oxide is oxidised
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When copper is heated in air, its surface turns black.
What is happening to the copper in this reaction?
Copper undergoes thermal decomposition
Copper is oxidised
Copper burns with a lilac flame
Copper is reduced
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Lead(II) oxide undergoes a number of different redox reactions.
In which of the following reactions is lead(II) oxide, PbO, not reduced?
PbO + Zn → Pb + ZnO
PbO + H2 → Pb + H2O
PbO + C → Pb + CO
2PbO + O2 → 2PbO2
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The following equations are all examples of redox reactions.
In which equation is the underlined substance being oxidised?
CO2 + C → 2CO
FeO + Mg → MgO + Fe
3CO + Fe2O3 → 2Fe + 3CO2
CuCO3 → CuO + CO2
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Three reactions are shown below.
NO + O3 → NO2 + O2
2C + O2 → 2CO
2MgO + O2 → 2MgO2
Which row correctly describes the process each reactant molecule undergoes?
| NO | O3 | MgO | |
| A | oxidised | reduced | oxidised |
| B | oxidised | oxidised | reduced |
| C | reduced | oxidised | oxidised |
| D | reduced | reduced | oxidised |
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What is the oxidation state of Fe in Fe2O3?
+2
-2
-3
+3
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Extended tier only
Which row correctly describes the process of reduction in terms of oxygen, electrons and oxidation state?
| oxygen is | electrons are | oxidation state is | |
| A | lost | added | unchanged |
| B | added | lost | increased |
| C | lost | added | decreased |
| D | added | lost | unchanged |
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A series of redox reactions are shown. What is the oxide that undergoes oxidation?
| 1 | 2CO + 2NO → 2CO2 + N2 |
| 2 | Fe2O3 + 2Al → Al2O3 + 2Fe |
| 3 | 2ZnO + C → 2Zn + CO2 |
| 4 | Fe2O3 + 3CO → 2Fe + 3CO2 |
CO
C
NO
Fe2O3
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Extended tier only
In which reaction is the reactant being reduced?
Mg → Mg2+ + 2ē
Mg2+ + 2ē → Mg
CrO → Cr2O3
C → CO2
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