ACE Your Redox Reactions

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| By Davincent
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  • 1/10 Questions

    Which change is oxidation?

    • Gain of electrons
    • Gain of hydrogen
    • Loss of oxygen
    • Loss of electrons
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About This Quiz

One of the ways we discovered to know if a redox reaction has occurred, you will find that the oxidation numbers of two elements has changed from the reactant side to the product side an example is the formation of hydrogen fluoride. This quiz will test your understanding of redox reactions, including oxidizing and reducing agents. Give it a try and ace your redox reactions test.

ACE Your Redox Reactions - Quiz

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  • 2. 

    Which change is reduction?

    • A decrease in oxidation state

    • Gain of oxygen

    • Loss of electrons

    • Loss of hydrogen

    Correct Answer
    A. A decrease in oxidation state
    Explanation
    A decrease in oxidation state is considered a reduction because it involves the gain of electrons, which is a characteristic of reduction reactions. When an atom or molecule undergoes a decrease in oxidation state, it is gaining electrons and becoming more negatively charged. This gain of electrons is associated with a reduction in the overall oxidation state of the atom or molecule. Therefore, a decrease in oxidation state is a reduction.

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  • 3. 

    What is the oxidation state of chromium in the oxide CrO3?

    • +3

    • -3

    • +6

    • -6

    Correct Answer
    A. +6
    Explanation
    The oxidation state of an element is a measure of the number of electrons it has gained or lost in a compound. In the oxide CrO3, there are three oxygen atoms, each with an oxidation state of -2. Since the overall charge of the compound is 0, the oxidation state of chromium (Cr) must be such that the sum of the oxidation states of all the atoms equals 0. By solving the equation 3(-2) + x = 0, we find that x = +6. Therefore, the oxidation state of chromium in CrO3 is +6.

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  • 4. 

    What is the oxidation state of sulphur in SO32-

    • -4

    • -2

    • +2

    • +4

    • +6

    Correct Answer
    A. +4
    Explanation
    The oxidation state of an element in a compound is a measure of the charge that element would have if all the shared electrons were assigned to the more electronegative atom. In SO32-, the oxidation state of oxygen is -2. Since the overall charge of the ion is -2, the sum of the oxidation states of all the atoms must equal -2. Therefore, the oxidation state of sulfur can be determined by solving the equation: x + 3(-2) = -2, where x is the oxidation state of sulfur. Solving this equation gives x = +4, indicating that the oxidation state of sulfur in SO32- is +4.

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  • 5. 

    Magnesium displaces lead ions from a solution of lead(II) sulphate. Which statement about this reaction is true?  

    • Lead (II) ions are oxidized.

    • Magnesium atoms are oxidised.

    • Lead (II) ions lose electrons.

    • Magnesium atoms gain electrons .

    Correct Answer
    A. Magnesium atoms are oxidised.
    Explanation
    In this reaction, magnesium displaces lead ions from the lead(II) sulphate solution. This means that magnesium is undergoing a redox reaction where it is being oxidized, since it is losing electrons in order to displace the lead ions. Therefore, the statement "Magnesium atoms are oxidised" is true.

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  • 6. 

    In which reaction is the first substance acting as a reducing agent?

    • Chlorine + iron(II) chloride ---> iron(III) chloride

    • Copper(II) oxide + hydrogen ---> copper + water

    • Hydrochloric acid + magnesium oxide ---> magnesium chloride + water

    • Carbon monoxide + zinc oxide ---> zinc + carbon dioxide

    Correct Answer
    A. Carbon monoxide + zinc oxide ---> zinc + carbon dioxide
    Explanation
    In the reaction "carbon monoxide + zinc oxide ---> zinc + carbon dioxide", carbon monoxide is acting as a reducing agent. This is because carbon monoxide is oxidized (loses electrons) while zinc oxide is reduced (gains electrons). The carbon monoxide transfers electrons to the zinc oxide, causing the reduction of zinc oxide to zinc and the oxidation of carbon monoxide to carbon dioxide.

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  • 7. 

    Hydrogen peroxide, H2O2, reacts with silver oxide according to the following equation.Ag2O(s) + H2O2(l) ---> 2Ag(s) + H2O(l) + O2(g)In this reaction, hydrogen peroxide behaves as

    • An acid

    • A catalyst

    • A dehydrating agent

    • An oxidising agent

    • A reducing agent

    Correct Answer
    A. A reducing agent
    Explanation
    In this reaction, hydrogen peroxide (H2O2) is acting as a reducing agent. A reducing agent is a substance that donates electrons to another substance, causing it to be reduced (gain electrons). In the given reaction, the hydrogen peroxide (H2O2) is being oxidized (loses electrons) to form water (H2O) and oxygen gas (O2). The silver oxide (Ag2O) is being reduced (gains electrons) to form silver metal (Ag). Therefore, hydrogen peroxide is behaving as a reducing agent in this reaction.

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  • 8. 

    Which compound, when added to aqueous iron(II) sulphate, takes part in a redox reaction?

    • Ammonia

    • Barium chloride

    • Acidified potassium manganate (VII)

    • Sodium hydroxide

    Correct Answer
    A. Acidified potassium manganate (VII)
    Explanation
    Acidified potassium manganate (VII) is the compound that takes part in a redox reaction when added to aqueous iron(II) sulphate. This is because potassium manganate (VII) is a strong oxidizing agent and can oxidize iron(II) ions to iron(III) ions. In this reaction, the manganese in potassium manganate (VII) is reduced from +7 oxidation state to +2 oxidation state, while the iron in iron(II) sulphate is oxidized from +2 oxidation state to +3 oxidation state. Therefore, a redox reaction occurs between the two compounds.

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  • 9. 

    Which one of the following substances is a reducing agent?

    • Argon

    • Oxygen

    • Carbon dioxide

    • Carbon monoxide

    Correct Answer
    A. Carbon monoxide
    Explanation
    Carbon monoxide is a reducing agent because it has a tendency to donate electrons to other substances. In a redox reaction, carbon monoxide can oxidize another substance by giving up electrons, while itself getting reduced. This is due to the presence of a polar covalent bond between carbon and oxygen, where oxygen is more electronegative and attracts the electron density towards itself, creating a partial positive charge on carbon. This makes carbon monoxide a good reducing agent.

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  • 10. 

    Acidified potassium dichromate (VI) can be used to detect the presence of ethanol vapour in the breath of a person who consumed alcohol. A colour change from orange to green is observed if ethanol is present.This shows that ethanol is

    • An alkali

    • An indicator

    • An oxidising agent

    • A reducing agent

    Correct Answer
    A. A reducing agent
    Explanation
    The correct answer is "a reducing agent." When acidified potassium dichromate (VI) is used to detect the presence of ethanol vapor, a color change from orange to green occurs. This color change indicates that ethanol is a reducing agent, as it causes the dichromate ion (Cr2O7 2-) in the potassium dichromate solution to be reduced to the green chromium(III) ion (Cr3+). Therefore, ethanol has the ability to donate electrons and cause a reduction reaction to occur.

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  • Current Version
  • Jun 07, 2024
    Quiz Edited by
    ProProfs Editorial Team
  • Jan 29, 2010
    Quiz Created by
    Davincent
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