Deck 14: Oxidation and Reduction

Question 1

Which of the following substances is the oxidizing agent in the chemical reaction ? 2CO + 2NO → 2CO₂ + N₂

A) CO
B) NO
C) CO₂
D) N
E) C

Answer 1

NO

Question 2

Rust formation is accelerated in the presence of salt water because_____.

A) oxygen is easily transported in water
B) salt water traps the oxygen at the surface of the metal
C) salt water conducts electricity
D) chloride ions also oxidize the surface of the metal
E) salt water contains a higher amount of oxygen than normal water

Answer 2

salt water conducts electricity

Question 3

Which substance is the reducing agent in this redox equation? HF + Cl₂ → F₂ + HCl

A) HF
B) Cl₂
C) F
D) HCl
E) None of these

Answer 3

HF

Question 4

Which of these occur(s) during oxidation?
I. Gaining electrons
II. Losing hydrogen
III. Losing oxygen

A) I only
B) II only
C) I and II
D) II and III
E) I, II, III

Question 5

Which of these occur(s) during reduction?
I. Losing electrons
II. Gaining hydrogen
III. Losing oxygen

A) I only
B) II only
C) III only
D) II and III
E) I and III

Question 6

Which of these statements about redox reactions is incorrect ?

A) Oxidation is the loss of oxygen.
B) Oxidation is the loss of electrons.
C) Reduction is the gain of electrons.
D) Oxidation is the loss of hydrogen.
E) Reduction is the gain of hydrogen.

Question 7

Which substance is the oxidizing agent in this redox reaction? Br ⁻ (aq) + MnO₄ ⁻ (aq) → Br₂(l) + Mn²⁺(aq)

A) Br ⁻
B) MnO₄ ⁻
C) Br₂
D) Mn²⁺
E) None of these

Question 8

Which of these occur(s) during oxidation?

A) Gaining electrons
B) Gaining hydrogen
C) Losing oxygen
D) All of these
E) None of these

Question 9

Which of these is a redox process?
I. Rusting of iron
II. Respiration
III. Burning hydrocarbons

A) I only
B) III only
C) I and II
D) I and III
E) I, II, and III

Question 10

Which of the following substances is the oxidizing agent in the chemical reaction ? PbCl₄ + SnCl₂ → PbCl₂ + SnCl₄

A) Pb
B) Sn
C) SnCl₂
D) PbCl₄
E) Cl₂

Question 11

Redox reactions involve the transfer of _____.

A) hydrogen
B) oxygen
C) protons
D) electrons
E) neutrons

Question 12

Which of these is not an application of oxidizing agents?

A) Disinfectants
B) Antiseptics
C) Household bleaches
D) Water treatment
E) Metal processing

Question 13

Which of these occurs(s) during reduction?

A) Gaining electrons
B) Gaining hydrogen
C) Losing oxygen
D) All of these
E) None of these

Question 14

Which substance is oxidized in this redox reaction? Br ⁻ (aq) + MnO₄ ⁻ (aq) → Br₂(l) + Mn²⁺(aq)

A) Br ⁻
B) MnO₄ ⁻
C) Br₂
D) Mn²⁺
E) None of these

Question 15

Which of these is not an oxidation-reduction reaction?

A) CuO(s) + H₂(g) → Cu(s) + H₂O(l)
B) CO₂(g) + H₂(g) → CO(g) + H₂O(l)
C) I ⁻ (aq) + NO₃ ⁻ (aq) → NO(g) + I ₂ (s)
D) Mn(OH)₂(s) + MnO₄ ⁻ (aq) → MnO₄^{2 −} (aq)
E) HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O (l)

Question 16

Which of these pairs is correctly matched?

A) Oxidation = the loss of oxygen
B) Reduction = the reducing agent
C) Oxidation = the loss of electrons
D) Oxidation = the gain of hydrogen
E) Reduction = the loss of hydrogen

Question 17

During oxidation-reduction reactions, the substance that loses electrons is _____and the substance that gains electrons is _____.

A) oxidized; reduced
B) reduced; oxidized
C) reduced; dissolved
D) reduced; accelerated
E) oxidized; dissolved

Question 18

Which of these statements about redox reactions is incorrect ?

A) Oxidation is the gain of oxygen.
B) Oxidation is the loss of electrons.
C) Reduction is the gain of electrons.
D) Oxidation is the gain of hydrogen.
E) Oxidation is the loss of hydrogen

Question 19

Which of these substances is the most common oxidizing agent?

A) CO
B) H₃O⁺
C) O₂
D) H₂
E) C

Question 20

Which substance is reduced in this redox equation? HF + Cl₂ → F₂ + HCl

A) HF
B) Cl₂
C) F
D) HCl
E) None of these

Question 21

Identify a true statement about photosynthesis.

A) Carbon is oxidized during photosynthesis.
B) Photosynthesis is an endothermic process.
C) Carbon dioxide and water are produced during photosynthesis.
D) Photosynthesis helps in the oxidation of glucose.
E) Photosynthesis can take place in the absence of sunlight.

Question 22

Which of these is/are oxidation-reduction reaction(s)?
I. PCl₃ + 3H₂O → 3HCl + H₃PO₃
II. Fe₂O₃ + 3CO → 2Fe + 3CO₂
III. CaCO₃ + HClO₃ → Ca(ClO₃)₂ + CO₂ + H₂O

A) I only
B) II only
C) I and II
D) I and III
E) I, II, and III

Question 23

Which of these substances are used in the reduction of metal ores?
I. CO
II. C
III. O₂
IV. H₂

A) I only
B) II only
C) III only
D) I and II
E) I, II, and III

Question 24

During respiration, glucose molecules are oxidized in the presence of _____to produce carbon dioxide and water.

A) O₂
B) H₂O
C) C
D) CO
E) H₂

Question 25

Which of these is correctly associated with the cathode?
I. Electrode  with a positive charge
II. Electrode at which a substance loses electrons
III. Electrode at which reduction occurs

A) I only
B) II only
C) I and II
D) I and III
E) I, II, and III

Question 26

Which of these is/are  not used as an antiseptic?

A) Hydrogen peroxide
B) Iodine
C) Benzoyl peroxide
D) Chlorine
E) All of these

Question 27

The series of redox reactions that provides animals energy is known as _____.

A) respiration
B) photosynthesis
C) the Haber process
D) metabolism
E) rusting

Question 28

During photosynthesis _____is _____to form glucose and oxygen.

A) carbon; oxidized
B) carbon; reduced
C) water; reduced
D) hydrogen; oxidized
E) oxygen; reduced

Question 29

Which of these substances is the most common reducing agent?

A) H₂
B) H₃O⁺
C) O₂
D) H₂O
E) CO

Question 30

Which of the following substances is the reducing agent in the chemical reaction ?
​
Fe₂O₃ + 3CO → 2Fe + CO₂

A) Fe₂O₃
B) CO
C) 2Fe
D) C
E) O₂

Question 31

Which of these equations correctly represents the photosynthesis process?

A) 3H₂ + N₂ → 2NH₃
B) Cu₂O + C → 2Cu + CO
C) Fe₂O₃ + 3CO → 2Fe + CO₂
D) C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O
E) 6CO ₂ + 6H ₂ O _light → C ₆ H ₁₂ O ₆ + 6O ₂

Question 32

Which of these pairs represents the reactants in photosynthesis?

A) Oxygen and carbon dioxide
B) Carbon dioxide and sugars
C) Water and carbon dioxide
D) Oxygen and water
E) Water and sugars

Question 33

Which statement about an electrochemical cell is incorrect ?

A) Reduction occurs at the anode.
B) The salt bridge is made from a porous material.
C) The electrode that acts as the anode carries a negative charge.
D) The current in the external wire always flows from anode to cathode.
E) Any spontaneous reaction can serve as a source of energy in a battery.

Question 34

The process by which plants generate glucose is known as _____.

A) respiration
B) photosynthesis
C) the Haber process
D) digestion
E) rusting

Question 35

During respiration, glucose molecules are _____ in the presence of oxygen to produce carbon dioxide and water.

A) dissolved
B) formed
C) reduced
D) oxidized
E) recycled

Question 36

Which of these are oxidation-reduction reactions?
I. 3H₂ + N₂ → 2NH₃
II. Cu₂O + C → 2Cu + CO
III. Fe₂O₃ + 3CO → 2Fe + CO₂
IV. 2K + Br₂ → 2KBr

A) I and III
B) III and IV
C) I and II
D) I, II, and III
E) I, II, III, and IV

Question 37

Which of these substances is/are  not a reducing agent used in industrial processes?

A) CO
B) H₂
C) O₂
D) C
E) Both C and CO

Question 38

Which of the following substances is oxidized in the chemical reaction ?
​
Fe₂O₃ + 3CO → 2Fe + CO₂

A) Fe₂O₃
B) CO
C) 2Fe
D) C
E) O₂

Question 39

Which of these statements about respiration is incorrect?

A) Carbon is oxidized during respiration.
B) Respiration is an exothermic process.
C) Carbon dioxide and water are produced during respiration.
D) Animals, including humans, use respiration to oxidize food for energy.
E) Carbon is reduced during respiration.

Question 40

Which of these equations correctly represents the Haber process?

A) 3H₂ + N₂ → 2NH₃
B) Cu₂O + C → 2Cu + CO
C) Fe₂O₃ + 3CO → 2Fe + CO₂
D) C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O
E) 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Question 41

How many electrons are transferred in the redox reaction of a typical flashlight battery?
Zn + 2MnO₂ + H₂O → Zn²⁺ + Mn₂O₃ + 2OH ⁻

A) 1
B) 2
C) 3
D) 4
E) 6

Question 42

Which of these processes can occur at the cathode in an electrochemical cell?

A) 2Br ⁻ → Br₂+ 2e ⁻
B) Cr → Cr³⁺ + 3e ⁻
C) Cu → Cu²⁺ + 2e ⁻
D) Li⁺ + 1e ⁻ → Li
E) H₂ + 2OH ⁻ → 2H₂O + 2e ⁻

Question 43

Which of these reactions occurs at the anode in this fuel cell?
​
2H₂ + O₂ → 2H₂O

A) 2H₂ + 4OH ⁻ → 4H₂O + 4e ⁻
B) O₂ + 2H₂ O + 4e ⁻ → 4OH ⁻
C) 4OH ⁻ + 4H⁺ → 4H₂O
D) 4OH ⁻ + 4e − → 4H₂O
E) None of these

Question 44

In electrochemical cells, _____ occurs at the anode and _____ occurs at the cathode.

A) oxidation; reduction
B) reduction; oxidation
C) oxidation; oxidation
D) gain of mass; oxidation
E) loss of mass; reduction

Question 45

Which of these statements correctly explains why batteries run out of energy?

A) The battery solutions boil off.
B) The battery solutions solidify.
C) The battery reactants are used up.
D) The external circuit becomes corroded.
E) The battery salt bridge reacts with the reactants.

Question 46

Which of these is not  a component in the hydrogen - oxygen fuel cell?

A) H₂
B) KOH
C) O₂
D) C
E) Pt

Question 47

Which of these substances is not found in a common Leclanch é dry cell?

A) Zn
B) MnO₂
C) NH₄Cl
D) H₂SO₄
E) C

Question 48

Which  of the following  statements about the lead-acid battery is incorrect?
​
Pb + PbO₂ + 4H⁺ + SO₄^{2 −} → 2PbSO₄ + 2H₂O

A) Lead is oxidized.
B) Lead oxide acts as the cathode.
C) Both the anode and cathode reactions result in the formation of PbSO₄.
D) Lead and lead oxide can be reformed from lead sulfate with the application of an outside electrical current.
E) Porous lead plates act as the cathode.

Question 49

Which of these is not an advantage of the alkaline battery over the Leclanch é dry cell?

A) Longer shelf life
B) Longer battery life
C) Less expensive
D) Less subject to corrosion
E) None of these

Question 50

Which of these is correctly associated with the anode?
I. Electrode with negative charges
II. Electrode at which a substance loses electrons
III. Electrode at which reduction occurs

A) I only
B) II only
C) I and II
D) I and III
E) I, II, and III

Question 51

Which of these methods is/are utilized to help prevent the rusting of iron?
I. Painting iron
II. Treating iron with sulfuric acid
III. Coating iron with a metal that is more likely to oxidize

A) I only
B) II only
C) I and III
D) I, II, and III
E) III only

Question 52

Which of these processes can occur at the anode in an electrochemical cell?

A) Br₂ + 2e ⁻ → 2Br ⁻
B) Zn → Zn²⁺ + 2e ⁻
C) Cu²⁺ + 2e ⁻ → Cu
D) Na⁺ + 1e ⁻ → Na
E) Pb⁴⁺ + 2e ⁻ → Pb²⁺

Question 53

Coating iron with a more oxidative metal than itself to prevent rusting is known as _____.

A) scrubbing
B) galvanizing
C) proofing
D) protecting
E) seal coating

Question 54

Which of these batteries has a continually renewable reactant source?

A) Zinc-copper batteries
B) Leclanch é dry cells
C) Lead-acid batteries
D) Alkaline batteries
E) Fuel cells

Question 55

Which substance acts as the cathode in the lead-acid automobile battery?
​
Pb + PbO₂ + 4H⁺ + SO₄^{2 −} → 2PbSO₄ + 2H₂O

A) Pb
B) PbO₂
C) 4H⁺
D) SO₄^{2 −}
E) H₂O

Question 56

Which of these is a possible anodic reaction that  occurs during the corrosion of iron?

A) 2Fe(s) → 2Fe²⁺(aq) + 4e ⁻
B) 2H⁺(aq) + 2e ⁻ → H₂(g)
C) 2H₂O(l) + 2e ⁻ → H₂(g) + 2OH ⁻ (aq)
D) O₂(g) + 2H₂O(l) + 4e ⁻ → 4OH ⁻ (aq)
E) SO₂(g) + O₂(g) + 2e ⁻ → SO₄^{2 −} (aq)

Question 57

Which substance acts as the anode in the lead-acid automobile battery?
​
Pb + PbO₂ + 4H⁺ + SO₄^{2 −} → 2PbSO₄ + 2H₂O

A) Pb
B) PbO₂
C) 4H⁺
D) SO₄^{2 −}
E) H₂O

Question 58

Which of these are the primary components in an automobile battery?

A) Lead and water
B) Copper and lead
C) Copper and zinc
D) Lead and sulfuric acid
E) Copper and sulfuric acid

Question 59

Which of these is a possible cathodic reaction that  occurs during the corrosion of iron?

A) 2Fe(s) → 2Fe²⁺(aq) + 4e ⁻
B) 2H⁺(aq) + 2e ⁻ → H₂(g)
C) 2H₂O(l) + 2e ⁻ → H₂(g) + 2OH ⁻ (aq)
D) O₂(g) + 2H₂O(l) + 4e ⁻ → 4OH ⁻ (aq)
E) SO₂(g) + O₂(g) + 2e ⁻ → SO₄^{2 −} (aq)

Question 60

The fraction of iron produced in the US to replace rusted iron is approximately _____.

A) 1/2
B) 1/3
C) 1/4
D) 1/5
E) 1/6

Question 61

Which of these is an antioxidant?

A) Vitamin E
B) Vitamin C
C) Beta carotene
D) All of these
E) None of these

Question 62

The best sources of antioxidants are _____.

A) fish and meat
B) fruits and vegetables
C) milk and honey
D) bread and butter
E) cereals and pulses

Question 63

Which of these metals is/are often used to help prevent the rusting of iron?
I. Al
II. Zn
III. Mg
IV. Na

A) I only
B) II only
C) I and III
D) I, II, and IV
E) I, II, and III

Question 64

In a lead-acid battery, the anode consists of porous lead plates in a(n) _____ solution.

A) HCl
B) H₂SO₄
C) AgNO₃
D) ZnNO₃
E) MgSO₄

Question 65

_____ is used as a coating  in the galvanization process.

A) Magnesium
B) Zinc
C) Chlorine
D) Iodine
E) Carbon

Question 66

The most common method used to protect underground pipes from rusting is _____.

A) covering them with paint
B) attaching a more active metal to them
C) treating them with sodium hydroxide
D) coating them with another metal whose oxide is less stable
E) treating them with hydrochloric acid

Question 67

Which  of the following  statements is incorrect ?

A) Zinc is used for galvanization because it loses electrons more easily than iron.
B) Zinc is used for galvanization because it forms a film that protects the iron.
C) Zinc is used for galvanization because it cannot be oxidized.
D) None of the se are incorrect statements.
E) All of these  are incorrect statements.

Question 68

A sliced apple will turn brown when exposed to air because  _____.

A) oxygen in the air oxidizes the chemicals present in the apple
B) oxygen in the air reduces the chemicals present in the apple
C) nitrogen in the air oxidizes the chemicals present in the apple
D) nitrogen in the air reduces the chemicals present in the apple
E) hydrogen in the air reduces the chemicals present in the apple

Question 69

Atoms or molecules with unpaired electrons are called _____.

A) inert elements
B) reducers
C) oxidizers
D) free radicals
E) antioxidants

Question 70

Which of the following is true of  free radicals?

A) They are very reactive.
B) They are very unstable.
C) They contribute to aging in humans.
D) They can alter biological molecules.
E) All of these   are true.

Question 71

Which of the following is true of fuel cells?

A) Efficiency of fuel cells ranges from 50% to 80%.
B) Reactants in fuel cells deplete over time.
C) Fuel cells can only be used in small devices.
D) A common fuel cell is the Leclanché dry cell.
E) All of these    are true of fuel cells.