Which of the following is the correct definition of oxidation?

A. Gain of electrons

B. Loss of electrons

C. Gain of protons

D. Loss of protons

In the reaction: 2Fe^3+ + 3S^2- -> Fe2S3, which species is reduced?

A. Fe^3+

B. S^2-

C. Fe2S3

D. None of the above

For balancing the following half-reaction in a basic solution: MnO4^- -> MnO2, which of the following steps is correct?

A. Add 2 electrons to the right side

B. Add 4 hydroxide ions to the left side

C. Add 2 water molecules to the right side

D. Add 2 electrons to the left side

Which of the following rules is NOT correct for assigning oxidation states?

A. The oxidation state of an atom in its elemental form is zero.

B. The oxidation state of hydrogen in most compounds is +1.

C. The oxidation state of oxygen in peroxides is -1.

D. The oxidation state of fluorine in all compounds is +1.

In the reaction: 2Al + 3Br2 -> 2AlBr3, what is the change in oxidation state of bromine?

A. From 0 to -1

B. From 0 to +1

C. From -1 to 0

D. From +1 to 0

a) What is meant by the term "oxidation state"? List two rules for assigning oxidation states to elements in a compound. [3]

b) In the reaction: 2H2 + O2 -> 2H2O, which element undergoes oxidation and which undergoes reduction? [2]

a) What is the half-reaction method used for in the context of redox reactions? [2]

b) Balance the following redox reaction in an acidic solution using the half-reaction method: MnO4^- + C2O4^2- -> Mn^2+ + CO2 [4]

a) How does balancing redox reactions in acidic solutions differ from balancing them in basic solutions? [3]

b) Balance the following redox reaction for a basic solution: ClO^- + Cr^3+ -> Cl^- + CrO4^2- [3]

a) Define the term "oxidation" in terms of electron transfer. [1]

b) For the reaction: 2Fe^3+ + 3S^2- -> Fe2S3, identify the species being oxidised and the species being reduced. [2]

c) What is the change in the oxidation state of iron in the above reaction? [2]

a) What is the significance of the half-reaction method in balancing redox reactions? [2]

b) Given the half-reaction: NO3^- -> NO + H2O, balance it in acidic conditions. [3]

c) How would you modify the balanced half-reaction if the conditions were basic instead of acidic? [2]

When balancing redox reactions in acidic solutions, which of the following is commonly added?

A. OH^- ions

B. H2O molecules

C. H^+ ions

D. Electrons

Which of the following is true about reduction?

A. It involves the loss of electrons.

B. It always occurs in the presence of an oxidising agent.

C. It involves the gain of electrons.

D. It results in an increase in oxidation state.

For the half-reaction: NO3^- -> NO, how many electrons are involved in the reduction process?

A. 1

B. 2

C. 3

D. 4

In a redox reaction, the substance that is reduced is called:

A. Reducing agent

B. Oxidising agent

C. Catalyst

D. None of the above

When balancing the following half-reaction in a basic solution: Cr2O7^2- -> Cr(OH)3, which of the following steps is correct?

A. Add 3 electrons to the right side

B. Add 7 hydroxide ions to the left side

C. Add 4 water molecules to the right side

D. Add 6 electrons to the left side

a) Explain the difference between oxidation state and oxidation number. [2]

b) In the compound KMnO4, determine the oxidation state of manganese. [2]

c) Why is KMnO4 often used as an oxidising agent in redox reactions? [2]

a) What role do transition metals play in redox reactions? [2]

b) Given the reaction: Cu^2+ + Zn -> Cu + Zn^2+, which element is the reducing agent? [2]

c) How can you determine the strength of an oxidising or reducing agent? [3]

a) What is the significance of assigning oxidation states to elements in a compound? [2]

b) For the reaction: 2Al + 3Br2 -> 2AlBr3, determine the element that undergoes reduction. [2]

c) Calculate the change in oxidation state for the element identified in part b). [2]

d) Why is it important to balance redox reactions? [3]

a) Describe the half-reaction method for balancing redox reactions in acidic solutions. [3]

b) Given the unbalanced reaction: MnO4^- + C2O4^2- -> Mn^2+ + CO2, balance it using the half-reaction method in acidic conditions. [4]

c) How would the balanced equation change in basic conditions? [2]

d) Why is it necessary to balance redox reactions separately for acidic and basic conditions? [2]

a) Define a "redox couple". [2]

b) Given the redox couple: Zn^2+/Zn, what does it represent in terms of oxidation and reduction? [2]

c) How can redox couples be used to determine the direction of a spontaneous reaction? [3]

d) Why are transition metals often involved in redox reactions? [2]