Oxidation and Reduction

Oxidation used to be defined as
1. the addition of oxygen to a substance.
2. the removal of oxygen from a substance.
3. the addition of hydrogen to a substance.
4. the gain of electrons by a substance.
Which one of the following statements about oxidation is correct?
1. In the reaction: C + O₂ ➞ CO₂ Carbon is oxidised.
2. In the reaction: CuO + H₂ ➞ CuO + H₂O Copper is oxidised.
3. In the reaction: 2Na + Cl₂ ➞ 2NaCl Chlorine is oxidised.
4. In the reaction: Zn + CuSO₄ ➞ ZnSO₄ + Cu Copper is oxidised.
Oxidation may be defined as the gain of oxygen, or the loss of
1. hydrogen
2. water
3. ions
4. positive charge
The removal of oxygen from a substance is known as
1. reduction
2. oxidation
3. diffusion
4. a reducing agent
Which one of these statements is incorrect?
1. Oxidation and reduction do not always occur together.
2. Oxidation of an element takes place when it loses electrons.
3. Reduction of an element occurs when it gains electrons.
4. When oxidation occurs, reduction also takes place.
Which one of the following satatements is correct?
1. Oxidation is loss of electrons
2. The oxidising agent is always oxidsised
3. Oxidation is gain of electrons
4. Reduction is loss of electrons
In the following reaction, which substance has been oxidised? PbO + H₂ ➞ Pb + H₂O
1. H₂
2. PbO
3. Pb
4. H₂O
Which one of the following statements is correct?
1. Oxidation is loss of electrons and increase in oxidation number.
2. Oxidation is gain of electrons and increase in oxidation number.
3. Reduction is gain of electrons and increase in oxidation number.
4. Reduction is loss of electrons and increase in oxidation number.
For the given reaction, which statement below is TRUE?
Zn + Cu²⁺ ➞ Zn²⁺ + Cu↓
1. Zinc loses 2 electrons and is oxidised.
2. Zinc loses 1 electron and is oxidised.
3. Zinc gains 2 electrons and is reduced.
4. Copper loses 2 electrons and is reduced.
The diagram below represents a redox reaction.

Which one of the following statements is correct?
1. A is oxidised.
2. B is oxidised
3. A is reduced
4. B is the reducing agent
Which one of the following is not a redox reaction?
1. CuO + H₂SO₄ ➞ Cu₂SO₄ + H₂O
2. PbO₂ + 4HCl ➞ PbCl₂ + Cl₂ + 2H₂O
3. 2Mg + O₂ ➞ 2MgO
4. 2Mg + CO₂ ➞ 2MgO + C
Oxidation may be defined as
1. increase in oxidation number
2. decrease in oxidation number
3. gain of an electron
4. gain of more than one electrons.
A substance that brings about oxidation in another substance is called
1. an oxidising agent
2. a reducing agent
3. a catalyst
4. a peroxide
A substance that brings about reduction in another substance is called
1. a reducing agent
2. an oxidising agent
3. a catalyst
4. a peroxide
In the given reaction, which is the oxidising agent?
Cu²⁺ + Mg ➞ Mg²⁺ + Cu
1. Cu²⁺
2. Mg
3. Mg²⁺
4. Cu
In the given reaction, which is the reducing agent?
Zn²⁺ + Mg ➞ Mg²⁺ + Zn
1. Mg
2. Zn²⁺
3. Mg²⁺
4. Zn
In a redox reaction, the substance that donates the electrons is known as
1. a reducing agent
2. an oxidising agent
3. an acid
4. an electrolyte
In a redox reaction, what happens to the reducing agent in terms of oxidation number?
1. Its oxidation number increases
2. Its oxidation number decreases
3. Nothing happens
4. It may increase or decrease
Reduction may be defined as
1. a decrease in oxidation number
2. an increase in oxidation number
3. a loss of one electron
4. a loss of more than one electrons.
Another name for an oxidation-reduction reaction is
1. a redox reaction
2. a chemical reaction
3. a neutralisation reaction
4. an endothermic reaction.
In the reaction shown, what element is being oxidised?
MnO₂ + 4HCl ➞ MnCl₂ + 2H₂ + Cl₂
1. Cl
2. Mn
3. H
4. O
Oxidising agents are used to kill fungi and bacteria.
Which one of the following is not an oxidising agent?
1. Magnesium
2. Hydrogen peroxide
3. Sodium hypochlorite
4. Fluorine
Which one of the following is not a property of an oxidising agent?
1. It tends to give away electrons.
2. Usually a non-metal or positive ion.
3. Causes oxidation reactions to take place.
4. It is reduced by gaining electrons.
Which one of the following is not a property of a reducing agent?
1. It causes oxidation reactions to take place.
2. It is usually a metal such as magnesium or a negative ion.
3. It loses electrons to another species.
4. It is itself oxidised.
In the reaction between copper ions and magnesium metal which species has been oxidised?
1. Mg
2. Mg²⁺
3. Cu²⁺
4. Cu
In the reaction between copper ions and magnesium metal what species is the reducing agent?
1. Mg
2. Mg²⁺
3. Cu²⁺
4. Cu
The group VII elements (Halogens) can all act as oxidising agents.
Which one of these is the strongest oxidising agent?
1. Fluorine
2. Chlorine
3. Bromine
4. Iodine
Chlorine is the second strongest oxidising agent of the halogens.
Which of the following can it not oxidise?
1. Fluorine
2. Iodine
3. Iron (II) ions
4. Sulfite ions (SO₃²⁻)
Which one of the following can bromine not oxidise?
1. Chlorine
2. Iodine
3. Iron (II) ions
4. Sulfite ions (SO₃²⁻)
Bromine can oxidise iron (II) ions.
Which one of the following equations best summarises this reaction?
1. Br₂ + 2Fe²⁺ ➞ 2Br⁻ + 2Fe³⁺
2. Br₂ + 2Fe³⁺ ➞ 2Br⁻ + 2Fe²⁺
3. 2Br⁻ + 2Fe²⁺ ➞ Br₂ + 2Fe³⁺
4. 2Br + 2Fe³⁺ ➞ 2Br⁻ + 2Fe²⁺
In the reaction below, what are the oxidising and reducing agents?
2KI + Cl₂ ➞ 2KCl + I₂
1. Cl₂ and KI respectively
2. KI and Cl₂ respectively
3. Cl₂ and KCl respectively
4. 2KI and I₂ respectively

Oxidation and Reduction

Multiple Choice Quiz