Chemistry 5070 · O Level
Electrolysis
100 practice questions on Electrolysis, with worked solutions and instant marking.
When aqueous copper(II) sulfate is electrolysed with copper electrodes, what are the correct products formed at the anode (positive electrode) and the cathode (negative electrode)?
May/June 2015
Concentrated aqueous sodium chloride is electrolysed with inert electrodes. Which statement about this electrolysis is correct?
May/June 2015
Aluminium is made by the electrolysis of molten aluminium oxide. Which statement correctly describes the process?
May/June 2015
Electrolysis is frequently used for extracting and purifying elements.
May/June 2015
When concentrated aqueous sodium chloride is electrolysed with carbon electrodes, which statement is correct?
May/June 2015
Water with a small amount of dilute sulfuric acid is electrolysed with carbon electrodes.
May/June 2015
Carbon electrodes are used to electrolyse aqueous copper(II) sulfate. Which observations would be seen?
May/June 2016
Which gases are present at the positive electrode during aluminium manufacture?
May/June 2016
Copper is purified by electrolysis. Which statement is incorrect?
May/June 2016
An aqueous sodium chloride solution of high concentration is electrolysed with inert electrodes until chlorine gas is no longer produced. What might the pH of the solution that remains be?
May/June 2016
Dilute sulfuric acid is electrolysed using inert electrodes. Which of the following statements are correct? 1 Hydrogen is given off at the negative electrode. 2 Oxygen is given off at the positive electrode. 3 Sulfur dioxide is given off at the positive electrode. 4 The acid becomes more concentrated.
May/June 2017
Concentrated aqueous calcium iodide is electrolysed in much the same way as concentrated aqueous sodium chloride. What would be produced at each electrode?
May/June 2017
Aluminium is produced by electrolysing molten aluminium oxide. Which row identifies the electrode where aluminium is produced and gives the correct equation for how it is formed?
May/June 2017
Dilute sulfuric acid is electrolysed using inert electrodes. Which of the following statements are correct?
May/June 2017
Caesium, $\text{Cs}$, belongs to the same group of the Periodic Table as sodium. What products are formed by the electrolysis of concentrated aqueous caesium chloride?
May/June 2017
The diagrams illustrate the apparatus used for the electrolysis of aqueous copper(II) sulfate. In experiment X, both electrodes are inert. In experiment Y, both electrodes are copper. At which electrodes does solid metal get deposited?
May/June 2017
Calcium chloride, CaCl$_2$, is classified as an ionic compound.
May/June 2017
Sodium oxide, $\text{Na}_2\text{O}$, is classified as an ionic compound.
May/June 2017
The diagrams illustrate an electrolysis experiment that uses inert electrodes. What might liquid $Y$ be?
May/June 2018
During the electrolysis of $\text{CuSO}_4\text{(aq)}$, what ionic equation represents the reaction occurring at the cathode?
May/June 2018
The diagrams illustrate an electrolysis experiment with inert electrodes. What might liquid Y be?
May/June 2018
Magnesium may be made by carrying out electrolysis on molten magnesium chloride, $\text{MgCl}_2$. What products are produced at the anode and at the cathode during the electrolysis of molten magnesium chloride?
May/June 2018
The diagram depicts a cell that may be used to obtain a metal from its oxide. Molten aluminium oxide, copper(II) oxide, lead(II) oxide and magnesium oxide are each electrolysed in separate cells. Every cell receives the same number of electrons. Which statement is correct?
May/June 2018
Which statement regarding the purification of copper using electrolysis is correct?
May/June 2019
During electrolysis of concentrated aqueous sodium chloride with inert electrodes, what substance is produced at the cathode, and what substance is produced at the anode?
May/June 2019
A student carries out an electrolysis experiment to investigate how the time for which an electric current is passed through $1\text{ mol dm}^{-3}$ copper(II) sulfate affects the mass of the cathode.
May/June 2019
The setup pictured is used to carry out the electrolysis of aqueous copper(II) sulfate.
May/June 2019
When an aqueous solution containing copper(II) nitrate and silver nitrate is electrolysed using pure copper electrodes, which half-equation shows the process taking place at the anode?
May/June 2021
The diagram illustrates the electrolysis of concentrated and dilute aqueous sodium chloride with inert electrodes. Gases are formed and gathered in test-tubes W, X, Y and Z. Which statements are correct?
May/June 2021
Molten sodium chloride is electrolysed. Which change takes place at the cathode?
May/June 2021
Inert electrodes are used to electrolyse lead(II) bromide. Which statement is correct?
May/June 2022
Dilute sulfuric acid undergoes electrolysis. Hydrogen gas and oxygen gas are formed. Which row shows the correct description of what occurs?
May/June 2022
Aluminium may be extracted by electrolysing aluminium oxide dissolved in molten cryolite. Which reactions occur during this electrolysis?
May/June 2022
This apparatus is employed to electrolyse dilute sulfuric acid, yielding hydrogen gas and oxygen gas.
May/June 2022
A concentrated aqueous solution of sodium chloride is electrolysed with inert electrodes. Which row shows the changes in this electrolysis and the reason for them?
May/June 2023
Aqueous copper(II) sulfate is electrolysed with copper electrodes. The current remains constant, and the anode is measured at regular intervals of time. Which graph is produced when the mass of the anode is plotted against time?
May/June 2023
This question concerns electrolysis.
May/June 2023
This question concerns electrolysis.
May/June 2023
Which row indicates the substances that are able to be electrolysed?
May/June 2024
The apparatus shown has been arranged to electroplate a steel key with copper. The key is not coated with copper. What change is needed to electroplate the key?
May/June 2024
Which reactions occur during the extraction of aluminium from aluminium oxide using carbon electrodes?
May/June 2024
The diagram illustrates a simple electrolytic cell. Which arrows indicate the movement of electrons?
May/June 2024
During the electrolysis of aqueous copper(II) sulfate using copper electrodes, which changes can be seen?
May/June 2024
Which statement concerning electrolysis is correct?
May/June 2025
The diagram illustrates an electrolysis experiment with inert electrodes. Which row indicates how the concentration of the electrolyte in L and in M changes as electrolysis continues?
May/June 2025
The diagram illustrates the electrolysis of molten lead bromide using inert electrodes. Which row identifies the particles that carry charge along each arrow?
May/June 2025
Which substances are formed at each electrode when aqueous copper(II) sulfate is electrolysed using copper electrodes?
May/June 2025
Graphite electrodes are used to electrolyse a concentrated aqueous solution of copper(II) bromide.
May/June 2025
Graphite electrodes are used to electrolyse a dilute aqueous solution of magnesium chloride.
May/June 2025
What happens during the electrolysis of dilute sulfuric acid?
Oct/Nov 2015
Aluminium is produced from aluminium oxide by electrolysis. In this process, cryolite is used. Which statement about cryolite is correct?
Oct/Nov 2015
The apparatus shown has been assembled to coat a steel key with copper. The key is not being covered with copper. What change must be made to plate the key?
Oct/Nov 2015
The diagrams below show the structures of graphite and boron nitride.
Oct/Nov 2015
A student uses the apparatus shown to carry out electrolysis on concentrated aqueous sodium chloride.
Oct/Nov 2015
An aqueous solution of copper(II) sulfate is electrolysed, with copper used as the positive electrode and carbon used as the negative electrode. Which row gives the correct information for this electrolysis?
Oct/Nov 2016
Four metals are electrolysed as molten salts. For one mole of atoms to be released in the electrolysis, the ions of which metal need the fewest electrons?
Oct/Nov 2016
Molten salts of four metals are electrolysed. For the ions of which metal is the fewest number of electrons needed to release one mole of atoms during electrolysis?
Oct/Nov 2016
A student carries out electrolysis on aqueous copper(II) sulfate with the apparatus shown. A solid forms at the cathode, and a gas forms at the anode.
Oct/Nov 2016
The apparatus in the diagram is used to carry out electrolysis of dilute sulfuric acid.
Oct/Nov 2016
Aluminium is obtained by electrolysing molten aluminium oxide. Which equation correctly represents the reaction taking place at the positive electrode?
Oct/Nov 2017
During the electrolysis of aqueous copper(II) sulfate with copper electrodes, which observations are correct?
Oct/Nov 2017
Three separate solutions were electrolysed with inert electrodes. solution 1: aqueous sodium chloride solution 2: concentrated hydrochloric acid solution 3: dilute sulfuric acid Which of these solutions gives hydrogen at the negative electrode?
Oct/Nov 2017
A simple cell may be constructed by using two different metals as the electrodes together with an aqueous solution as the electrolyte. Which statements about simple cells are correct?
Oct/Nov 2017
Magnesium may be obtained by electrolysing molten magnesium chloride, $\text{MgCl}_2$. What are the equations for the reactions taking place at the positive electrode and at the negative electrode?
Oct/Nov 2017
Three separate solutions were electrolysed by using inert electrodes. solution 1: aqueous sodium chloride solution 2: concentrated hydrochloric acid solution 3: dilute sulfuric acid Which of the solutions gives hydrogen at the negative electrode?
Oct/Nov 2017
Copper(II) sulfate is classified as an ionic compound.
Oct/Nov 2017
NaCl, sodium chloride, and magnesium chloride, MgCl$_2$, are both ionic compounds.
Oct/Nov 2017
The diagrammed apparatus is used for the electrolysis of dilute hydrochloric acid.
Oct/Nov 2017
A student performs experiments with two different electrolytes in the apparatus illustrated.
Oct/Nov 2017
What is seen during the electrolysis of aqueous copper(II) sulfate with carbon electrodes?
Oct/Nov 2018
Electrolysis is used to coat a metal statue with silver. The statue acts as an electrode in a suitable electrolyte. Which row is correct?
Oct/Nov 2018
What observations are made during the electrolysis of aqueous copper(II) sulfate when carbon electrodes are used?
Oct/Nov 2018
Four electrolysis processes are given below. 1 the electrolysis of concentrated aqueous sodium chloride 2 the electrolysis of dilute sulfuric acid 3 the extraction of aluminium from pure aluminium oxide 4 the purification of copper using aqueous copper(II) sulfate Which processes generate oxygen at one of the electrodes?
Oct/Nov 2018
When zinc is placed in aqueous nickel(II) nitrate, $\text{Zn}(s)+\text{Ni(NO}_3)_2(aq)\rightarrow \text{Zn(NO}_3)_2(aq)+\text{Ni}(s)$.
Oct/Nov 2018
Magnesium undergoes a reaction with aqueous copper(II) sulfate. $\text{Mg(s)} + \text{CuSO}_4\text{(aq)} \rightarrow \text{MgSO}_4\text{(aq)} + \text{Cu(s)}$
Oct/Nov 2018
A student carries out two electrolysis experiments with the apparatus shown.
Oct/Nov 2018
The diagram illustrates an electrolysis experiment with inert electrodes. Which row indicates how the concentration of the electrolyte changes in L and in M as electrolysis continues?
Oct/Nov 2019
Molten sodium chloride is electrolysed. Which equation shows the reaction taking place at the cathode correctly?
Oct/Nov 2019
The diagram illustrates the apparatus used in an electrolysis experiment. From the apparatus shown, which electrolyte would produce colourless gases at both electrodes?
Oct/Nov 2019
A student carries out electrolysis on three solutions using the apparatus shown.
Oct/Nov 2019
A student sends an electric current through aqueous copper(II) sulfate electrolyte, using an inert anode and a copper cathode.
Oct/Nov 2019
Aqueous copper(II) sulfate is electrolysed with copper electrodes. The current remains constant, and the anode is weighed at regular intervals. Which graph is produced if the anode mass is plotted against time?
Oct/Nov 2020
A concentrated aqueous solution of sodium chloride is electrolysed using inert electrodes. Which row indicates what occurs in this electrolysis and the reason for it?
Oct/Nov 2020
Aqueous copper(II) sulfate is electrolysed with copper electrodes. The current stays constant, and the anode is weighed at regular intervals of time. Which graph is obtained when the anode’s mass is plotted against time?
Oct/Nov 2020
The diagram illustrates the electrolysis of a mixture containing aqueous copper(II) nitrate, $\text{Cu(NO}_3)_2\text{(aq)}$, together with aqueous silver nitrate, $\text{AgNO}_3\text{(aq)}$. Electrodes X and Y are inert. Copper is above silver in the reactivity series. It follows that ……1…… is first deposited at electrode ……2……. Which words correctly fill gaps 1 and 2?
Oct/Nov 2020
Aluminium is obtained from its ore by electrolysis. Which statement about the electrodes that are used is correct?
Oct/Nov 2020
Diagrams of chlorine and sodium chloride are shown here. In the chlorine diagram, the particles are Cl-Cl molecules. In the sodium chloride diagram, the particles form a lattice of alternating $\text{Na}^+$ and $\text{Cl}^-$ ions.
Oct/Nov 2020
A student aims to electroplate a metal spoon with a coating of copper. Plan how the student should carry out the experiment.
Oct/Nov 2020
A student examines two separate aqueous electrolytes with the apparatus illustrated.
Oct/Nov 2020
Which statement concerning electrolysis reactions is correct?
Oct/Nov 2021
The apparatus shown has been arranged to coat a steel key with copper by electroplating. No copper is deposited on the key. Which alteration is needed so that the key can be plated?
Oct/Nov 2021
During the extraction of aluminium from aluminium oxide, the three reactions below occur. 1 $\text{Al}^{3+} + 3e^- \rightarrow \text{Al}$ 2 $2\text{O}^{2-} \rightarrow \text{O}_2 + 4e^-$ 3 $\text{C} + \text{O}_2 \rightarrow \text{CO}_2$ Which reactions occur at the positive electrode?
Oct/Nov 2021
Which statement concerning the electrolysis of solutions is correct?
Oct/Nov 2021
The apparatus shown has been arranged to plate a steel key with copper, but the key does not become coated with copper. Which change is needed in order to plate the key?
Oct/Nov 2021
During the extraction of aluminium from aluminium oxide, these three reactions occur. 1 $\text{Al}^{3+} + 3e^- \rightarrow \text{Al}$ 2 $2\text{O}^{2-} \rightarrow \text{O}_2 + 4e^-$ 3 $\text{C} + \text{O}_2 \rightarrow \text{CO}_2$ Which of these reactions occur at the positive electrode?
Oct/Nov 2021
An aqueous solution of copper(II) sulfate is electrolysed with inert electrodes. Which statement is correct?
Oct/Nov 2022
A concentrated aqueous solution of sodium chloride is electrolysed with inert electrodes. Which equation represents the reaction taking place at the anode?
Oct/Nov 2022
Which pair of equations correctly shows the reactions occurring at the anode and at the cathode during the electrolysis of molten silver bromide?
Oct/Nov 2022
Dilute aqueous solutions of potassium chloride and magnesium chloride are combined. An aliquot of the resulting mixture is electrolysed with inert electrodes. What products may be formed at each electrode?
Oct/Nov 2022
The table presents several statements about electrolysis together with the explanation for why each statement is correct. Which row contains a correct statement and the correct explanation for why it is correct?
Oct/Nov 2022