Quiz 1

Chemistry Redox reaction

Quiz Type

Practice

Subject

Molecular Biology

Level

Level 100

Questions

10 questions

Created By

Stella Boadi

Quick Rules

Time limit: 50 minutes
Multiple attempts are not allowed
All questions must be answered to submit

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Question 1 of 10

Question 1

Basic multiple choice Understanding

In a simple redox reaction, if substance A is oxidized, what can be inferred about substance B?

It is also oxidized

It cannot participate in redox reactions

It must be reduced

Correct

It remains unchanged

Explanation

If substance A is oxidized, it means it loses electrons, which provides those electrons to substance B, indicating that B must be reduced.

Question 2

Basic multiple choice Understanding

Which of the following statements is true regarding oxidation in redox reactions?

It involves the loss of neutrons

It involves the gain of electrons

It involves the loss of electrons

Correct

It occurs only in acids

Explanation

Oxidation is characterized by the loss of electrons, resulting in an increase in oxidation state.

Question 3

Basic multiple choice Remembering

What does the term 'redox' in a redox reaction refer to?

Reduction and oxidation

Correct

Reactants and products

Solvents and solutes

Acids and bases

Explanation

The term 'redox' is a combination of 'reduction' and 'oxidation', which are two chemical processes that occur simultaneously in redox reactions.

Question 4

Basic multiple choice Remembering

In a redox reaction, which process involves the gain of electrons?

Oxidation

Reduction

Correct

Decomposition

Combustion

Explanation

Reduction is the chemical process where a substance gains electrons, leading to a decrease in oxidation state.

Question 5

Basic multiple choice Remembering

What type of agent is responsible for causing the reduction of another substance in a redox reaction?

Reducing agent

Correct

Oxidizing agent

Catalyst

Inert gas

Explanation

A reducing agent donates electrons to another substance, thereby causing that substance to be reduced.

Question 6

Complex multiple choice Understanding

In a redox reaction, zinc is oxidized, and copper ions are reduced. If a solution contains zinc metal and copper sulfate, which statement best describes the transfer of electrons in this reaction?

Zinc loses electrons to copper, increasing its oxidation state.

Correct

Copper gains electrons from zinc while decreasing its oxidation state.

Correct

Zinc and copper exchange protons to form water as a byproduct.

Zinc is reduced during the reaction while copper is oxidized.

Explanation

In this redox reaction, zinc undergoes oxidation (loses electrons), and copper(II) ions undergo reduction (gain electrons). Therefore, zinc's oxidation state increases while copper's decreases. The statement about protons is incorrect since redox reactions involve the transfer of electrons, not protons. The last statement is incorrect as it misrepresents the oxidation states of zinc and copper.

Question 7

Complex multiple choice Understanding

Consider a redox reaction where iron(III) oxide reacts with aluminum. If the aluminum reduces the iron(III) oxide to iron, which of the following explains the underlying electron transfer process in this scenario?

Aluminum donates electrons to iron ions, reducing them while being oxidized to aluminum ions.

Correct

Iron ions donate electrons to aluminum, leading to iron being oxidized and aluminum reduced.

Both aluminum and iron ions remain unchanged, simply forming a compound without any electron transfer.

This reaction involves a transfer of protons rather than electrons to form aluminum oxide and iron.

Explanation

In this reaction, aluminum acts as the reducing agent; it donates electrons to the iron(III) ions, effectively reducing the iron ions to metallic iron while itself being oxidized to aluminum ions. The second statement incorrectly reverses the roles of aluminum and iron. The third statement is incorrect because the process involves significant changes in oxidation states due to electron transfer. The last statement mischaracterizes the reaction as one involving protons instead of electrons.

Question 8

Case based multiple choice Understanding

[Case Scenario] A group of chemistry students is conducting an experiment where they mix hydrochloric acid (HCl) with zinc metal (Zn). During the reaction, the students observe the release of hydrogen gas and the formation of zinc chloride (ZnCl2). They note that zinc is being oxidized while hydrochloric acid is being reduced, as hydrogen ions gain electrons. Question: What is the primary redox reaction taking place in this experiment?

Zinc is oxidized as it loses electrons to hydrogen ions.

Correct

Zinc is reduced while hydrochloric acid is oxidized.

Hydrochloric acid is oxidized, and zinc remains unchanged during the reaction.

Both zinc and hydrochloric acid undergo oxidation reactions simultaneously.

Explanation

In this redox reaction, zinc metal donates electrons, which is the defining characteristic of oxidation, while hydrogen ions from hydrochloric acid gain electrons, making them reduced. The balanced reaction confirms zinc oxidation and hydrogen ion reduction, which exemplifies the redox process.

Question 9

Case based multiple choice Understanding

[Case Scenario] During a laboratory demonstration, a teacher presents a redox reaction where iron (Fe) is reacting with copper sulfate (CuSO4). The students observe that iron displaces copper, resulting in the formation of iron(II) sulfate (FeSO4) and solid copper. The teacher highlights that iron is more reactive than copper in the galvanic series. Question: In this redox reaction, which substance is being reduced?

Iron (Fe)

Copper ions (Cu²⁺)

Correct

Sulfuric acid (SO4²⁻)

Iron(II) sulfate (FeSO4)

Explanation

In this reaction, iron displaces copper from copper sulfate, leading to the reduction of copper ions (Cu²⁺) to solid copper (Cu) as iron (Fe) is oxidized. The displacement demonstrates a clear redox reaction where copper is reduced due to the gain of electrons.

Question 10

Case based multiple choice Understanding

[Case Scenario] A chemist is studying a redox reaction in which potassium permanganate (KMnO4) is used as an oxidizing agent in acidic solution, reacting with ferrous ion (Fe²⁺) to form ferric ion (Fe³⁺) and manganese(II) ion (Mn²⁺). The chemist wants to determine the stoichiometry of the balanced equation and calculate the number of moles of KMnO4 required for complete reaction with 0.5 moles of Fe²⁺. Question: Based on the stoichiometric coefficients typically found in this reaction, how many moles of KMnO4 are needed to react with 0.5 moles of Fe²⁺?

0.5 moles

1 mole

0.25 moles

Correct

2 moles

Explanation

In the redox reaction between KMnO4 and Fe²⁺, the stoichiometric ratio indicates that it takes 1 mole of KMnO4 to oxidize 5 moles of Fe²⁺. Thus, with 0.5 moles of Fe²⁺, only 0.1 moles of KMnO4 would be needed for complete reaction, not 0.25 moles. The answer requires careful interpretation of the chemical reaction's stoichiometry.