Chemistry 0620 · IGCSE
Electrolysis
100 practice questions on Electrolysis, with worked solutions and instant marking.
When concentrated hydrochloric acid undergoes electrolysis, gases P and Q are produced. Which gases are P and Q?
Feb/March 2016
The electrolysis of concentrated hydrochloric acid is illustrated. Which statement explains what happens to the electrons during the electrolysis?
Feb/March 2016
The apparatus shown can be used to electrolyse molten potassium bromide. It has graphite electrodes dipped into the molten potassium bromide.
Feb/March 2016
Four substances undergo electrolysis. The substances are concentrated aqueous sodium chloride, concentrated hydrochloric acid, molten lead(II) bromide and molten sodium oxide. Which statement about these electrolysis reactions is correct?
Feb/March 2017
The diagram illustrates the electrolysis of aqueous copper(II) sulfate. Which statement is correct?
Feb/March 2017
Four solutions are electrolysed separately. In which two experiments is a colourless gas released at the anode?
Feb/March 2017
Chlorine and sodium hydroxide are made by electrolysing concentrated aqueous sodium chloride.
Feb/March 2017
Which of the following statements about electrolysis reactions is correct?
Feb/March 2018
Aluminium is obtained from aluminium oxide by electrolysis. Carbon dioxide is produced in this process. Which equation represents the production of carbon dioxide during the extraction of aluminium from aluminium oxide by electrolysis?
Feb/March 2018
A solution of copper(II) sulfate may be electrolysed with either copper electrodes or carbon electrodes. Which of the following statements are correct?
Feb/March 2018
What feature of the diagram indicates that molten magnesium has a lower density than molten magnesium chloride?
Feb/March 2018
Sodium chloride is a standard example of an ionic compound.
Feb/March 2018
As shown, two electrolysis experiments were performed. The graphite electrodes are numbered 1-4. In one experiment, molten sodium chloride is used, while in the other, concentrated aqueous sodium chloride is used. Which row gives the products formed at the electrodes in these experiments?
Feb/March 2019
Which substance is not formed during the electrolysis of concentrated aqueous sodium chloride?
Feb/March 2019
In the electrolysis of aqueous copper(II) sulfate with copper electrodes, what ionic half-equations represent the reactions occurring at each electrode?
Feb/March 2019
This question concerns chromium and chromium compounds.
Feb/March 2019
Which statement regarding electrolysis is correct?
Feb/March 2020
Which of the following statements concerning the electrolysis of molten lead(II) bromide are correct?
Feb/March 2020
An aqueous solution of copper(II) sulfate is electrolysed with carbon electrodes. Which statement is correct?
Feb/March 2020
Electrolysis of dilute sulfuric acid generates gases at both electrodes.
Feb/March 2020
Three substances are electrolysed with inert electrodes. Which of these substances gives hydrogen at the negative electrode?
Feb/March 2021
In the electrolysis of dilute sulfuric acid, hydrogen gas is produced at the cathode. What is the ionic half-equation for this reaction?
Feb/March 2021
The ionic half-equation for oxygen being produced in the electrolysis of aluminium oxide is given below. $x\text{O}^{2-} \rightarrow \text{O}_2 + y\text{e}^-$ What values do $x$ and $y$ have?
Feb/March 2021
Sodium is made by electrolysis.
Feb/March 2021
The diagram illustrates an electrolysis circuit. At which electrode does hydrogen form?
Feb/March 2023
An electrolysis experiment is carried out with carbon electrodes. Hydrogen and oxygen are produced at the electrodes. What is the electrolyte?
Feb/March 2023
A concentrated aqueous copper(II) sulfate solution is electrolysed using copper electrodes. Which ionic half-equation shows the reaction occurring at the cathode?
Feb/March 2023
Potassium iodide is classified as an ionic compound.
Feb/March 2023
Concentrated aqueous sodium chloride is electrolysed with graphite electrodes. Which substance is produced at the cathode?
Feb/March 2024
Which statements account for why a water tap made of steel is electroplated with copper?
Feb/March 2024
Concentrated aqueous sodium chloride and dilute sulfuric acid are each electrolysed with inert electrodes. Which row shows the product formed at the cathode in each electrolysis?
Feb/March 2024
Electrolysis is used to break electrolytes down. Which rows are correct for each electrolyte?
Feb/March 2024
Which products are produced when dilute sulfuric acid is electrolysed?
Feb/March 2025
The diagram illustrates an experiment used to electroplate a nickel spoon with silver. Which row correctly states the positive electrode, the negative electrode and the electrolyte?
Feb/March 2025
Three aqueous solutions, L, M and N, are electrolysed with inert electrodes. L is concentrated hydrochloric acid. M is concentrated aqueous sodium chloride. N is dilute aqueous sodium chloride. Which of the solutions give a pale yellow-green gas at the anode?
Feb/March 2025
Dilute sulfuric acid is electrolysed with inert electrodes. What ionic half-equations show the reactions occurring at each electrode?
Feb/March 2025
This question concerns ionic compounds.
Feb/March 2025
The quantities of gases P and Q produced when substance X undergoes electrolysis are shown below. What is substance X?
May/June 2016
Which substances are formed at the electrodes when dilute sulfuric acid is electrolysed with inert electrodes?
May/June 2016
Electricity is sent separately through concentrated hydrochloric acid, concentrated aqueous sodium chloride and dilute sulfuric acid. In which rows are the electrolysis products named correctly?
May/June 2016
Which reactions might occur at the anode in electrolysis?
May/June 2016
Aluminium is produced by the electrolysis of aluminium oxide. The diagram shows the electrolysis cell. Which statement about the process is incorrect?
May/June 2016
The diagram illustrates the electrolysis of molten zinc chloride, $\text{ZnCl}_2$. Which statement is correct?
May/June 2016
The diagram illustrates a method used to copper-plate a pan. Which equation shows the reaction at the cathode?
May/June 2016
Silver electroplating of steel objects is carried out in three stages. step 1 A layer of copper is deposited on the object. step 2 A layer of nickel is deposited on the object. step 3 A layer of silver is deposited on the object.
May/June 2016
Hydrogen may be produced from methane through steam reforming. $\text{CH}_4(g) + \text{H}_2\text{O}(g) \rightleftharpoons \text{CO}(g) + 3\text{H}_2(g)$ This reaction is performed with a nickel catalyst at temperatures from 700 ^{\circ}C to 1100 ^{\circ}C and at a pressure of one atmosphere. The forward reaction is endothermic, meaning heat is absorbed.
May/June 2016
A concentrated aqueous solution of sodium chloride is electrolysed. Which substance is formed in the largest amount at the positive electrode (anode)?
May/June 2017
An aqueous sodium chloride solution with a high concentration can be electrolysed. Which statement is correct?
May/June 2017
What substances are first formed at each electrode when concentrated aqueous sodium chloride is electrolysed?
May/June 2017
Which statement concerning electrolysis is correct?
May/June 2017
Which of the following statements about electrolysis is correct?
May/June 2017
Which statement is correct about electrolysis?
May/June 2017
What can be seen at each electrode when molten lead(II) bromide is electrolysed with platinum electrodes?
May/June 2018
The electrolysis of molten lead(II) bromide is illustrated below. Which statement explains what occurs at the negative electrode?
May/June 2018
Which substance is formed at each electrode when molten rubidium chloride undergoes electrolysis using platinum electrodes?
May/June 2018
Copper(II) sulfate solution is electrolysed with copper electrodes. Which statement is correct?
May/June 2018
In the electrolysis of dilute sulfuric acid with inert electrodes, what are the ionic half-equations for the processes occurring at each electrode?
May/June 2018
Aluminium metal is obtained from aluminium oxide by electrolysis. Which statement about the extraction process is not correct?
May/June 2018
Aqueous copper(II) sulfate is electrolysed with copper electrodes. Which statement about this electrolysis is incorrect?
May/June 2018
Electrolysis is carried out on dilute sulfuric acid with inert electrodes. What ionic half-equations represent the reactions occurring at each electrode?
May/June 2018
An aqueous solution of copper(II) sulfate is electrolysed with copper electrodes. Which of the following statements is correct?
May/June 2018
Dilute sulfuric acid undergoes electrolysis with inert electrodes. What are the ionic half-equations for the reactions occurring at each electrode?
May/June 2018
Complete the electrolysis sentence by choosing words from the list. breakdown, compound, electricity, electroplating, element, gaseous, heat, molten Electrolysis is the ................. of an ionic ................. when ................. or in aqueous solution by the passage of ................. .
May/June 2018
As electrolysis takes place, gas is formed at both electrodes. Finish the diagram to show the method used to collect the gases.
May/June 2018
State the name used for the positive electrode.
May/June 2018
At room temperature, potassium reacts with bromine to produce potassium bromide.
May/June 2018
Calculate the empirical formula of the hydrated nickel(II) iodide crystals.
May/June 2018
Four substances are electrolysed with inert electrodes. Which row shows the products at the electrodes?
May/June 2019
Separate electrolysis is carried out on samples of dilute sulfuric acid and concentrated hydrochloric acid. Which row shows the product formed at each electrode in the electrolysis of both substances?
May/June 2019
During electrolysis, which substance does not give off a gas at both electrodes?
May/June 2019
Aluminium metal is obtained from aluminium oxide through electrolysis. Which ionic half-equation shows a reaction occurring at the electrode named?
May/June 2019
Which statement concerning the electrolysis of copper(II) sulfate solution with carbon electrodes is correct?
May/June 2019
Aluminium is obtained by electrolysis, as illustrated. Which row gives the ionic half-equations at the cathode and at the anode?
May/June 2019
The diagram illustrates the electrolysis of an aqueous solution of X with inert electrodes. Hydrogen is formed at the cathode, and chlorine is formed at the anode. What is X?
May/June 2019
During the production of aluminium by electrolysis, aluminium oxide is dissolved in molten cryolite. What is the purpose of using cryolite?
May/June 2019
An aqueous copper(II) sulfate solution was electrolysed with copper electrodes. Which equation correctly shows the reaction occurring at the anode?
May/June 2019
Ionic compounds in solution can be decomposed by electrolysis.
May/June 2019
In two different experiments, an electric current was passed through concentrated aqueous sodium chloride and through molten lead(II) bromide. What would be observed in both experiments?
May/June 2021
In two separate experiments, an electric current was passed through concentrated aqueous sodium chloride and through molten lead(II) bromide. What would occur in both experiments?
May/June 2021
In two separate experiments, electricity was passed through concentrated aqueous sodium chloride and molten lead(II) bromide. What would occur in both experiments?
May/June 2021
In two separate experiments, electricity was passed through concentrated aqueous sodium chloride and molten lead(II) bromide. What would be observed in both experiments?
May/June 2021
What is the ionic half-equation for the reaction taking place at the cathode when molten lead(II) bromide is electrolysed?
May/June 2021
In two different experiments, an electric current was passed through concentrated aqueous sodium chloride and molten lead(II) bromide. What would occur in each experiment?
May/June 2021
Aluminium is obtained from its ore using electrolysis. Which equation shows the reaction taking place at the anode during the electrolysis?
May/June 2021
In two separate experiments, an electric current was passed through concentrated aqueous sodium chloride and through molten lead(II) bromide. What would occur in each experiment?
May/June 2021
State which products are formed at the negative electrode and the positive electrode during this electrolysis.
May/June 2021
Dilute sulfuric acid is electrolysed with carbon electrodes. State the products formed at the negative electrode and at the positive electrode.
May/June 2021
Concentrated hydrochloric acid is electrolysed with carbon electrodes.
May/June 2021
In the apparatus shown, a student performs an electrolysis experiment. The student makes use of dilute aqueous sodium chloride.
May/June 2021
Sodium and fluorine react together to make sodium fluoride, NaF.
May/June 2021
The diagram illustrates the electrolysis of concentrated hydrochloric acid and concentrated aqueous sodium chloride with carbon electrodes. At which electrodes is hydrogen formed?
May/June 2022
The diagram illustrates the electrolysis of concentrated hydrochloric acid and concentrated aqueous sodium chloride with carbon electrodes. At which electrodes is hydrogen formed?
May/June 2022
The diagram illustrates the electrolysis of concentrated hydrochloric acid and concentrated aqueous sodium chloride with carbon electrodes. At which electrodes is hydrogen formed?
May/June 2022
The diagram illustrates the electrolysis of concentrated hydrochloric acid and concentrated aqueous sodium chloride with carbon electrodes. At which electrodes is hydrogen formed?
May/June 2022
An aqueous solution of copper(II) sulfate is electrolysed with copper electrodes. What is the ionic half-equation for the process at the cathode?
May/June 2022
The flow diagram shows a section of the process used to produce sulfuric acid and its electrolysis. What are the identities of gases 1, 2 and 3?
May/June 2022
The diagram illustrates the electrolysis of concentrated hydrochloric acid and concentrated aqueous sodium chloride with carbon electrodes. At which electrodes does hydrogen form?
May/June 2022
The diagram illustrates the electrolysis of aqueous copper(II) sulfate with inert electrodes. Which arrow indicates the direction of electron movement in the circuit?
May/June 2022
The diagram illustrates the electrolysis of concentrated hydrochloric acid and concentrated aqueous sodium chloride with carbon electrodes. At which electrodes is hydrogen gas formed?
May/June 2022
Aluminium is produced from aluminium oxide by electrolysis. Which row gives the ionic half-equations at each electrode and states the function of cryolite in this process?
May/June 2022