IGCSE Coordinated Chemistry Workout 24

The diagram shows a helium atom.

Which particles in the helium atom have approximately the same mass?

• electron and proton only

• electron and neutron only

• proton and neutron only

• electron, proton and neutron

Which change is a physical change?

• burning fuels

• electrolysis of dilute sulfuric acid

• melting ice

• neutralising acids

Diagrams W, X, Y and Z represent the structures of four different compounds.

Which row identifies these compounds? Answers are shown in the same order as the molecules in the diagram.

• NO₂ CO₂ H₂O SO₂

• NO₂ H₂O SO₂ CO₂

• SO₂ CO₂ NO₂ H₂O

• SO₂ NO₂ CO₂ H₂O

The diagram shows the electrolysis of dilute sulfuric acid.

Which substance is produced at the negative electrode?

• hydrogen

• oxygen

• sulfur dioxide

• water

Lime is manufactured by heating limestone. Lime is used to control the acidity of soil.

Which types of chemical change occur in these two reactions?

• A

• B

• C

• D

Nitrogen from the air is used to manufacture ammonia.

nitrogen + hydrogen → ammonia

Why is a catalyst used in this reaction?

• Nitrogen from the air is not pure.

• Nitrogen is a gas at room temperature.

• Nitrogen is a non-metallic element.

• Nitrogen is not very reactive.

Hydrochloric acid reacts with excess solid sodium carbonate to form sodium chloride, water and carbon dioxide gas.

Which method is used to investigate the speed of this reaction?

• Measure the pH of the reaction mixture after 10 minutes.

• Measure the time taken for all of the solid to dissolve.

• Measure the total volume of gas produced.

• Measure the volume of gas produced every minute.

The table shows the results of some tests on a compound.

What is the compound?

• iron(II) chloride

• iron(II) sulfate

• iron(III) chloride

• iron(III) sulfate

An element is a solid at room temperature and does not conduct electricity.

What is the proton number of this element?

• 11

• 19

• 35

• 53

Some of the gases found in polluted air are listed.

1 carbon monoxide

2 carbon dioxide

3 nitrogen dioxide

4 sulfur dioxide

Which gases cause the erosion of buildings?

• 1 and 3

• 1 and 4

• 2 and 4

• 3 and 4