MCQs — Electrochemistry

Practice questions for Chemistry.

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Question 1

In terms of oxygen transfer, oxidation is defined as:

A. Loss of oxygen

B. Gain of oxygen

C. Loss of hydrogen

D. Gain of electrons

Question 2

In terms of oxygen transfer, reduction is defined as:

A. Gain of oxygen

B. Loss of oxygen

C. Gain of hydrogen

D. Loss of electrons

Question 3

In the reaction Fe2O3 + 3CO -> 2Fe + 3CO2, carbon monoxide (CO) is:

A. Losing oxygen, so it is being reduced

B. Gaining oxygen, so it is being oxidized

C. Neither gaining nor losing oxygen

D. Gaining hydrogen

Question 4

In the reaction Fe2O3 + 3CO -> 2Fe + 3CO2, iron(III) oxide (Fe2O3) is:

A. Gaining oxygen, so it is being oxidized

B. Losing oxygen, so it is being reduced

C. Unaffected by the reaction

D. Losing hydrogen

Question 5

Carbon first reacts with air in a blast furnace before reacting with iron oxide mainly because:

A. Carbon must first form carbon monoxide, which is the actual substance that then reduces the iron oxide

B. Iron oxide cannot react with any gas directly

C. Air prevents any reaction from occurring

D. Carbon dioxide is required to melt the iron ore

Question 6

Since oxidation and reduction always occur together, the overall reaction Fe2O3 + 3CO -> 2Fe + 3CO2 is best classified as a(n):

A. Acid-base reaction

B. Redox (oxidation-reduction) reaction

C. Purely physical change

D. Decomposition reaction only

Question 7

In the reaction CuO + Zn -> Cu + ZnO, based on oxygen transfer, copper(II) oxide (CuO) is:

A. Gaining oxygen, so it is being oxidized

B. Losing oxygen, so it is being reduced

C. Remaining completely unchanged

D. Losing hydrogen

Question 8

In the same reaction (CuO + Zn -> Cu + ZnO), based on oxygen transfer, zinc (Zn) is:

A. Losing oxygen, so it is being reduced

B. Gaining oxygen, so it is being oxidized

C. Unaffected by the reaction

D. Gaining hydrogen

Question 9

In terms of hydrogen transfer, oxidation is defined as:

A. Gain of hydrogen

B. Loss of hydrogen

C. Gain of oxygen only

D. Gain of electrons only

Question 10

In terms of hydrogen transfer, reduction is defined as:

A. Loss of hydrogen

B. Gain of hydrogen

C. Loss of oxygen only

D. Loss of electrons only

Question 11

Acetylene (C2H2) is commercially used, when burned, to produce a very hot flame mainly for the purpose of:

A. Refrigeration

B. Cutting and welding metals

C. Water purification

D. Food preservation

Question 12

In the combustion reaction 2C2H2 + 5O2 -> 4CO2 + 2H2O, acetylene (C2H2) is:

A. Gaining hydrogen, so it is being reduced

B. Losing hydrogen, so it is being oxidized

C. Unaffected in terms of hydrogen

D. Gaining oxygen only, with no hydrogen change

Question 13

In the same combustion reaction (2C2H2 + 5O2 -> 4CO2 + 2H2O), oxygen (O2) is:

A. Losing hydrogen, so it is being oxidized

B. Gaining hydrogen, so it is being reduced

C. Completely unreactive

D. Losing oxygen atoms

Question 14

The same combustion reaction can be analyzed using either the oxygen-transfer or the hydrogen-transfer definition of oxidation and reduction because:

A. A single reaction can often be described from more than one valid perspective, since oxidation/reduction can involve oxygen, hydrogen, and/or electron transfer simultaneously

B. Only one definition can ever be correct for any given reaction

C. Hydrogen and oxygen transfer are always completely unrelated processes

D. Combustion reactions never involve oxygen transfer

Question 15

It is possible for a single substance in a reaction to be simultaneously gaining oxygen and losing hydrogen because:

A. Gaining oxygen and losing hydrogen are two separate but related descriptions of oxidation, and a substance can undergo both changes at the same time

B. Oxygen and hydrogen can never be involved in the same reaction

C. A substance can only ever lose one type of atom at a time

D. Gaining oxygen always prevents hydrogen loss

Question 16

In terms of electron transfer, oxidation is defined as:

A. Gain of electrons

B. Loss of electrons

C. Gain of oxygen only

D. Loss of oxygen only

Question 17

In terms of electron transfer, reduction is defined as:

A. Loss of electrons

B. Gain of electrons

C. Loss of hydrogen only

D. Gain of oxygen only

Question 18

When the reaction CuO + Zn -> Cu + ZnO is rewritten as a full ionic equation, the oxide ions (O2-) are considered:

A. The main reactive species

B. Spectator ions, since they appear unchanged on both sides

C. Oxidizing agents

D. Reducing agents

Question 19

The oxide ions are removed to give the net ionic equation Cu2+ + Zn -> Cu + Zn2+ mainly because:

A. Spectator ions undergo no change and take no real part in the actual electron-transfer reaction

B. Oxide ions are too reactive to include

C. Removing ions is always required, regardless of their role

D. Oxide ions do not actually exist in solution

Question 20

In the net ionic equation Cu2+ + Zn -> Cu + Zn2+, the copper ion (Cu2+) is:

A. Losing 2 electrons to form Cu, so it is being oxidized

B. Gaining 2 electrons to form Cu, so it is being reduced

C. Unchanged throughout the reaction

D. Acting as a spectator ion

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