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Quiz Chapter 1: Redox Equilibrium

10 questions · Form 5 Chemistry Bab 1: Redox Equilibrium

10 questions · plays in fullscreen

Full Question List & Answer Key

Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.

1. A substance that acts as an oxidising agent will always:

  1. Lose electrons and undergo oxidation
  2. Gain electrons and undergo reduction
  3. Increase its oxidation number
  4. Donate protons to the solution
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Answer: B

An oxidising agent oxidises other substances by accepting/gaining electrons, meaning it undergoes reduction.

2. Which of the following reagent converts Fe²⁺ ions to Fe³⁺ ions?

  1. Zinc powder
  2. Acidified Potassium Dichromate(VI) solution
  3. Sulfur dioxide gas
  4. Magnesium ribbon
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Answer: B

Acidified Potassium Dichromate(VI) is a strong oxidising agent capable of oxidising Fe²⁺ to Fe³⁺.

3. What is oxidation defined as in terms of electron transfer?

  1. Gain of electrons
  2. Loss of electrons
  3. Sharing of electrons
  4. No change in electrons
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Answer: B

Oxidation is defined as the loss of electrons during a chemical process.

4. Which metal is used as a sacrificial anode to protect underground iron pipes from rusting?

  1. Copper
  2. Tin
  3. Magnesium
  4. Silver
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Answer: C

Magnesium has a more negative E° value than iron, making it more electropositive. It corrodes preferentially, protecting the iron.

5. What are the essential conditions required for iron to rust?

  1. Water and Nitrogen
  2. Carbon dioxide and Oxygen
  3. Water and Oxygen
  4. Acid and Sunlight
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Answer: C

Rusting of iron requires simultaneous presence of water and oxygen.

6. In a voltaic cell, at which electrode does oxidation occur?

  1. Cathode
  2. Salt Bridge
  3. Anode
  4. External wire
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Answer: C

Oxidation always takes place at the anode in both voltaic and electrolytic cells.

7. Which of the following elements has an oxidation number of zero?

  1. Cl⁻ in NaCl
  2. H in H₂O
  3. O in O₂ gas
  4. Fe in FeSO₄
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Answer: C

Free uncombined elements (such as elemental O₂ gas) have an oxidation state of 0.

8. Which metal can be extracted from its oxide by reduction with carbon in a blast furnace?

  1. Aluminium
  2. Magnesium
  3. Iron
  4. Potassium
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Answer: C

Iron is less reactive than carbon, so carbon can reduce iron(III) oxide to iron in a blast furnace. Metals like Al, Mg, and K are more reactive than carbon and require electrolysis.

9. During the electrolysis of dilute sodium chloride solution using carbon electrodes, which gas is liberated at the anode?

  1. Chlorine gas
  2. Oxygen gas
  3. Hydrogen gas
  4. Sodium vapor
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Answer: B

In dilute NaCl solution, OH⁻ ions have a lower discharge potential (less positive E°) than Cl⁻ ions, so OH⁻ ions are discharged at the anode to produce Oxygen gas.

10. What is the function of the salt bridge in a voltaic cell?

  1. To allow electron flow between electrodes
  2. To allow ion migration and maintain electrical neutrality
  3. To prevent oxidation at the anode
  4. To increase the resistance of the cell
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Answer: B

A salt bridge allows the movement of ions between half-cells to complete the circuit and maintain electrical neutrality.

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