IGCSE Electrochemistry MCQ

When substance X is electrolysed, the amount of gases P and Q formed is shown. What is substance X?

• concentrated aqueous sodium chloride

• concentrated hydrochloric acid

• dilute sulfuric acid

• molten lead(II) bromide

Answer explanation

P is hydrogen and Q is oxygen.

This is because P is double the amount of Q.

(hydrogen and oxygen are produced in the ratio 2:1(H2O))

From the answers, the only electrolyte that can produce hydrogen and oxygen through electrolysis is dilute sulfuric acid.

What are the products at the electrodes when dilute sulfuric acid is electrolysed using inert electrodes?

• anode: hydrogen, cathode: oxygen

• anode: oxygen, cathode: hydrogen

• anode: sulfur, cathode: oxygen

• anode: sulfur dioxide, cathode: hydrogen

Electricity is passed separately through concentrated hydrochloric acid, concentrated aqueous sodium chloride and dilute sulfuric acid.

In which rows are the electrolysis products correctly named?

• 1, 2, and 3

• 1 and 2 only

• 1 and 3 only

• 2 and 3 only

What describes the electrolysis of molten potassium bromide?

• anode: bromine, cathode: hydrogen

• anode: bromine, cathode: potassium

• anode: hydrogen, cathode: bromine

• anode: potassium, cathode: bromine

The diagram shows a failed attempt to copper-plate a pan.

Which action will plate the pan with copper?

• Cooling the copper sulfate solution in an ice bath

• Heating the copper sulfate solution to boiling point

• Increasing the voltage from 3V to 6V

• Making the pan the cathode and copper the anode

The diagram shows the electroplating of a steel object.

A student made the following statements.

Which statements are correct?

• 1,2, and 3

• 1 and 2 only

• 1 and 3 only

• 2 and 3 only

The diagram shows the electroplating of a steel object.

A student made the following statements.

Which statements are correct?

• 1,2, and 3

• 1 and 2 only

• 1 and 3 only

• 2 and 3 only

An object is electroplated with silver using an aqueous silver salt as the electrolyte.

Which set of conditions is used?

• A

• B

• C

• D

Which metal could not be used for electroplating by using an aqueous solution?

• Chromium

• Copper

• Silver

• Sodium