Science Quiz

The diagram shows an electrical cable. Which statement about the substances used is correct?

• The coating is plastic because it conducts electricity well.

• The core is copper because it conducts electricity well.

• The core is copper because it is cheap and strong.

• The core is iron because it is cheap and strong.

Answer explanation

The correct statement is that the core is copper because it conducts electricity well. Copper is a highly efficient conductor, making it ideal for electrical cables, unlike iron, which is less conductive.

Benjamin is conducting an experiment where 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

Answer explanation

In concentrated hydrochloric acid, hydrogen and chlorine are produced (Row 1). In dilute sulfuric acid, hydrogen and oxygen are produced (Row 3). Sodium chloride (Row 2) produces hydrogen and chlorine, but the products are not correctly named.

David is studying the properties of materials used in overhead power cables. Which statement explains why a particular substance is used?

• Aluminium has a low density and is a good conductor of electricity.

• Ceramic is a good conductor of electricity.

• Steel can rust in damp air.

• Steel is more dense than aluminium.

Answer explanation

Aluminium is chosen for overhead power cables because it has a low density, making it lightweight, and it is an excellent conductor of electricity, ensuring efficient power transmission.

Noah is conducting an experiment in the lab, where he is performing the electrolysis of concentrated hydrochloric acid and concentrated aqueous sodium chloride using carbon electrodes. At which electrode(s) is hydrogen produced?

• electrode 1 only

• electrodes 1 and 3

• electrode 2 only

• electrodes 2 and 4

Answer explanation

Hydrogen is produced at the cathode during electrolysis. In concentrated hydrochloric acid, hydrogen is generated at electrode 1, and in concentrated sodium chloride, it is produced at electrode 3. Thus, the correct answer is electrodes 1 and 3.

Oliver and Sophia are conducting an experiment in their chemistry lab. They are using electrolysis to separate elements from a solution. At which electrodes are copper and hydrogen formed?

• anode, anode

• anode, cathode

• cathode, anode

• cathode, cathode

Answer explanation

Copper is formed at the cathode during electrolysis, where reduction occurs, while hydrogen is produced at the anode, where oxidation takes place. Thus, the correct answer is cathode for copper and anode for hydrogen.

Michael is working on a project where an object is electroplated with silver using an aqueous silver salt as the electrolyte. Which set of conditions should he use?

• The object to be electroplated is the anode, the other electrode is made from carbon.

• The object to be electroplated is the anode, the other electrode is made from silver.

• The object to be electroplated is the cathode, the other electrode is made from carbon.

• The object to be electroplated is the cathode, the other electrode is made from silver.

Answer explanation

In electroplating, the object to be plated is the cathode, where reduction occurs. Silver ions from the electrolyte are reduced and deposit on the cathode. The anode is typically made of silver, providing the metal ions needed for plating.

Hannah is conducting an experiment to plate a spoon with silver. Which statement is not correct?

• Silver would stick to the spoon because it is a very reactive metal.

• The electrolyte would be a silver salt dissolved in water.

• The metal electrode would be made from silver.

• The spoon would be connected to the negative terminal of the power supply.

Answer explanation

The statement is incorrect because the spoon should be connected to the positive terminal of the power supply, making it the anode, while the negative terminal is for the metal electrode.

Emma is conducting an experiment in her chemistry lab. She wants to know which metal could not be used for electroplating by using an aqueous solution. Can you help her?

• chromium

• copper

• silver

• sodium

Answer explanation

Sodium cannot be used for electroplating with an aqueous solution because it is highly reactive and does not easily deposit as a metal. In contrast, chromium, copper, and silver can be effectively electroplated from their solutions.

During a science experiment, Luna and Noah are investigating the products formed at the electrodes when a concentrated solution of sodium chloride is electrolysed. What products do they expect to see?

• hydrogen, chlorine

• hydrogen, oxygen

• sodium, chlorine

• sodium, oxygen

Answer explanation

During the electrolysis of concentrated sodium chloride solution, water is reduced at the cathode to produce hydrogen gas, while chloride ions are oxidized at the anode to produce chlorine gas. Thus, the products are hydrogen and chlorine.

Ava is conducting an experiment in her chemistry lab. She wants to know which products are formed at the anode and cathode when electricity is passed through molten lead(II) bromide.

• bromide ions, lead ions

• bromine molecules, lead atoms

• lead atoms, bromine molecules

• lead ions, bromide ions

Answer explanation

When electricity is passed through molten lead(II) bromide, lead ions are reduced at the cathode to form lead atoms, while bromide ions are oxidized at the anode to produce bromine molecules. Thus, the correct answer is bromine molecules, lead atoms.