Cambridge IGCSE · Chemistry (0620)

Redox: Practice Questions

5 multiple-choice questions marked as you go, and 5 written questions with worked solutions. All on Redox.

10 questions24 marksFree, no account

Question 1

1 mark

Which statement correctly describes an oxidation reaction according to the transfer of oxygen?

Question 2

1 mark

In the chemical reaction: \( 2Fe + 3Cl_2 \rightarrow 2FeCl_3 \), which species is being oxidized and what is the reason?

Question 3

1 mark

When an unknown liquid X is added to a solution of aqueous potassium iodide, the solution turns from colorless to brown. Which statement about liquid X is correct?

Question 4

1 mark

What is the oxidation number of iron in iron(III) oxide, \(Fe_2O_3\)?

Question 5

1 mark

When acidified aqueous potassium manganate(VII) is used to test for sulfite ions, \(SO_3^{2-}\), the purple color disappears. Which statement correctly describes the role of the sulfite ions?

Question 6

2 marks

Define oxidation and reduction in terms of the gain or loss of oxygen atoms.

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Question 7

4 marks

In the reaction \(2\text{Fe} + 3\text{Cl}_2 \rightarrow 2\text{FeCl}_3\), identify which species is oxidised and explain your answer in terms of electron transfer.

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Question 8

4 marks

Manganese(IV) oxide reacts with hot concentrated hydrochloric acid to produce manganese(II) chloride, chlorine gas, and water.

(a) State the oxidation number of manganese in \(\text{MnO}_2\) and in \(\text{MnCl}_2\).
(b) Identify the oxidizing agent in this reaction, and explain your choice in terms of changes in oxidation number.

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Question 9

3 marks

Redox reactions involve simultaneous oxidation and reduction. Consider the following reaction between copper(II) oxide and hydrogen gas:

\(\text{CuO(s)} + \text{H}_2\text{(g)} \rightarrow \text{Cu(s)} + \text{H}_2\text{O(g)}\)

(a) Define oxidation in terms of oxygen gain or loss.
(b) Identify the substance that is reduced in this reaction.
(c) Explain your answer to part (b) by referring to the movement of oxygen.

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Question 10

6 marks

Redox reactions can be defined in terms of electron transfer and oxidation numbers. Consider the reaction between zinc metal and aqueous copper(II) sulfate:

\(\text{Zn(s)} + \text{CuSO}_4\text{(aq)} \rightarrow \text{ZnSO}_4\text{(aq)} + \text{Cu(s)}\)

(a) Write the ionic half-equation for the oxidation of zinc.
(b) State the oxidation number of sulfur in the sulfate ion (\(\text{SO}_4^{2-}\)). Show your working.
(c) Identify the oxidising agent in this reaction and explain your choice in terms of electron transfer.

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