Preview: Cambridge Lower Secondary Science Workbook 8

Cambridge Lower Secondary

Science STAGE 8: WORKBOOK

Aidan Gill, Heidi Foxford, Dorothy Warren

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Contents How to use this book

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Chapter 1 • Obtaining food 1.1 Food from plants 1.2 A balanced diet 1.3 Malnutrition 1.4 Digestion Self-assessment Test-style questions

6 9 13 15 17 19

Chapter 2 • Respiration and circulation 2.1 Human circulatory system 2.2 Human respiratory system 2.3 Smoking and health 2.4 Transport of water and mineral salts in plants Self-assessment Test-style questions

22 25 28 30 33 35

Chapter 3 • Reproduction and growth 3.1 Reproductive systems 3.2 Puberty 3.3 Foetal growth and development 3.4 Drugs, disease and diet Self-assessment Test-style questions

37 40 42 45 47 49

Chapter 4 • Elements, compounds and mixtures 4.1 More on changes of state 4.2 Gas pressure and diffusion 4.3 Atoms, elements and the Periodic Table 4.4 Compounds and formulae 4.5 Separating mixtures Self-assessment Test-style questions

53 56 61 63 67 71 73

Chapter 6 • Chemical reactions 6.1 Using word equations 6.2 Reactions with acid 6.3 Reactions with oxygen Self-assessment Test-style questions

86 90 92 95 97

Chapter 7 • Light 7.1 Light rays 7.2 Reflection 7.3 Refraction 7.4 Coloured light Self-assessment Test-style questions

101 104 106 109 112 114

Chapter 8 • Sound 8.1 How sounds are made 8.2 How we hear sounds 8.3 Loudness and pitch Self-assessment Test-style questions

117 120 123 126 128

Chapter 9 • Measuring motion 9.1 Measuring distance and time 9.2 Speed and average speed 9.3 Distance–time graphs Self-assessment Test-style questions

131 134 138 141 142

Chapter 10 • Magnets 10.1 Magnets and magnetic materials 10.2 Electromagnets Self-assessment Test-style questions

146 149 152 154

Chapter 5 • Metals, non-metals and corrosion 5.1 Metals and non-metals 5.2 Corrosion and rusting Self-assessment Test-style questions

76 79 82 84

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Chapter 4: Elements, compounds and mixtures

4.1 More on changes of state Learning outcomes

•

To use particle theory to explain the properties of solids, liquids and gases and what happens during changes in state

1.

Draw three lines to match the particle diagram to the correct state of matter.

gas

liquid

2.

solid

[2 marks]

The particle diagrams below show how the particle arrangement changes during a change of state.

Name the change of state.

Tick one box.

Melting 3.

Evaporating

Freezing

Condensing

[1 mark]

Complete the sentences by choosing the correct words from the list. freeze

look

fixed

Solids have a definite

evaporate

flow

random

slide

shape

because the particles all have positions and are all touching.

Liquids

because the particles can

past each other.

4.

Worked Example

When chocolate is left in the warm sun, it starts to melt.

Use your knowledge of particle theory to explain why.

Heat energy transferred from the Sun to the chocolate increases the vibration of the chocolate particles. ✔ This increased vibration breaks down some of the attractive forces between the chocolate particles in the solid. ✔ The solid melts to give liquid chocolate where the chocolate particles can slide past each other easily. ✔

[4 marks] Remember Use your scientific knowledge to explain means to apply what you have learned in science to a new context or problem.

[3 marks]

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5.

Look at the diagram.

Remember Compare means to describe the similarities and differences between at least two things.

It shows a kettle of boiling water.

B

A

Compare the water particles at point A with those at point B. At point A water is in the

state. The particles are rapidly

. At point B water is in the

state.

The particles 6.

[4 marks]

Sometimes the pipes carrying water in houses in northern Europe split open or burst.

Burst water pipes are more common in winter than in summer.

Explain why.

[2 marks] 7.

Challenge

Gases and liquids take on the shape of their container.

Bromine gas completely fills the bottle but liquid bromine just covers the bottom of the bottle.

Explain why.

[2 marks]

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8.

Practical

4 Investigating changes of state Morag and Jesse were investigating how the temperature of icy water changes as it is heated over a period of time.

Temperature (°C)

At the start of the investigation they made a prediction. It is shown in the predicted graph below.

a

100 90 80 70 60 50 40 30 20 10 0

Time (minutes)

Write down a prediction based on this graph.

[1 mark]

The girls then collected some data using the following method: • Place some crushed ice and water in a beaker • Stir the contents of the beaker • Measure and record the temperature using a thermometer • Heat the beaker of ice (keep stirring)

Next the girls drew a results graph using the data they had collected. b

Describe what happens to the temperature of the ice and water during the experiment.

Temperature (°C)

• Record the temperature every minute until the water boils

100 80 60 40 20 0 –5

5

10

15

20

25

Time (minutes)

[4 marks]

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c

Compare the results graph with the predicted graph.

[2 marks] d

Use your knowledge of particle theory to explain the differences.

[4 marks]

4.2 Gas pressure and diffusion Learning outcomes

• •

To use particle theory to explain gas pressure and diffusion To explain how temperature affects the rate of diffusion

1.

Diffusion will occur if there is a difference in: Tick one box.

2.

Mass

Pressure

Temperature

Concentration

[1 mark]

The two particle diagrams show the same gas at different pressures.

A

B

State which diagram shows the gas at high pressure.

[1 mark]

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