crown hills community college year 8 science homework

Crown Hills Community College

Year 8

Science Homework

Name ________________________ Form ________

Teacher ______________________ Room ________

Year 8 – Science Homework

Content

Page Title Date set Due date Completed 1 Forces keywords 2 Forces extended question 3 Matter keywords 4 Matter extended question 5 Organisms keywords 6 Organisms extended question 7 Electromagnets keywords 8 Electromagnets extended question 9 Waves keywords 10 Waves extended question 11 Ecosystems keywords 12 Ecosystems extended question 13 Reactions keywords 14 Reactions extended question 15 Energy keywords 16 Energy extended question 17 Earth keywords 18 Earth extended question 19 Genes keywords 20 Genes extended question 21 Wind turbine variables 22 Solar panel variables 23 Variables 24 Washing powder experiment 25 Modified plants experiment 26 Spring extension variables 27 Photosynthesis graph 28 Hydrocarbon graph 29 Limestone experiment 30 Line and bar graphs 31 Carbon dioxide graph 32 pH graph 33 Temperature graph 34 Oxygen bubbles experiment

35-36 Hair dye experiment 37-38 Pollen grain experiment

Year 8 – Science Homework Forces keywords

Name: _____________________ Form: _________ Completed on time

moment

Single force which can replace all the forces acting on an object and have the

same effect.

resultant force

A measure of the ability of a force to

rotate an object about a pivot.

drag force

The point beyond which a spring will not return to its original length when the

force is removed.

law of moments

Force extending or pulling apart.

elastic limit

The force acting on an object moving through air or water that causes it to

slow down.

tension

An object is in equilibrium if the clockwise moments equal the

anticlockwise moments.

pressure

Force squashing or pushing together, which changes the shape of an object.

compression

The ratio of force to surface area, in N/m2, and how it causes stresses in

solids.

1.


Forces extended question

Two students are trying to explain how a chair cushion supports your weight. One student says the seat just squashes the same amount whoever sits on it and the other says it depends on how heavy the person is.

The diagram shows the inside of a chair cushion.

Explain how a chair cushion supports your weight and which student is correct. In your answer you should include diagrams to show the forces on the springs as someone is sitting down and when they are sitting still.

(6 marks)

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Teacher: _______________________________________ Effort Grade

Merits awarded

2.


Forces extended question

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Year 8 – Science Homework Matter keywords


atom A one- or two-letter code for an element

that is used by scientists in all countries.

chemical formula A substance made up of atoms of two

or more elements, strongly joined together.

chemical symbol A group of two or more atoms, strongly

joined together.

compound A formula that shows the relative

number of atoms of each element in a compound.

element A table of all the elements, in which elements with similar properties are

grouped together.

molecule A substance that cannot be broken

down into other substances.

Periodic Table A molecule made by joining up

thousands of smaller molecules in a repeating pattern. These can be natural

or synthetic.

polymer The smallest part of an element that

can exist.

3.


Matter extended question

Describe the chemical reactions of Group 1 and Group 7 elements.

Your answer should include: examples of word equations for a specific Group 1 element the reaction between a Group 7 element and iron word equations for any reactions you describe. (6 marks)

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Merits awarded

4.


Matter extended question

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Year 8 – Science Homework organisms keywords


addiction The transfer of gases between an organism and its environment.

bile A drug that slows down the body’s

reactions by slowing down the nervous system.

deficiency A lack of minerals, that causes

poor growth.

gas exchange A need to keep taking a drug in order to

feel normal.

drug Enzyme that breaks down lipids into

fatty acids and glycerol.

alcohol Substance that breaks fat into

small droplets.

respiratory system Chemical substance that affects the

way your body works.

lipase The organs involved in gas exchange.

5.


Organisms extended question

Describe the main events that take place inside your body in order to turn a meal into simple food molecules. (6 marks)

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Merits awarded

6.


Organisms extended question

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Year 8 – Science Homework Electromagnets keywords


magnet

A region in which there is a force on a

magnet or magnetic material.

magnetic pole

A device that uses an electromagnet to make sound from a varying potential

difference. Turns an electrical signal into a pressure wave of sound.

magnetic field

A material with a magnetic field around it in which a magnetic material

experiences a force.

solenoid

A device that uses an electromagnet

to break a circuit if the current is too big.

core

Wire wound into a tight coil, part of an

electromagnet.

electromagnet

A non-permanent magnet turned on and off by controlling the current

through it.

loudspeaker

The ends of a magnetic field, called

north-seeking and south-seeking poles.

circuit breaker

Soft iron metal which the solenoid is

wrapped around.

7.


Electromagnets extended question

Describe how you would investigate how the number of coils affects the strength of an electromagnet, using this equipment:

iron core; wire; power supply; paper clips (small, medium, or large)

Your answer should include:

a method

how you control the variables

whether you should repeat

whether you should use small, medium, or large paper clips

safety advice. (6 marks)

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Merits awarded

8.


Electromagnets extended question

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Year 8 – Science Homework Waves keywords


electromagnetic spectrum

The part of a longitudinal wave where

the air particles are close together.

gamma ray

When waves join together so that they

add up or cancel out.

compression

Waves with the lowest frequency in the electromagnetic spectrum, used

for communicating.

transverse wave

A wave in which the direction of vibration is the same as that of the

wave.

longitudinal wave

The range of wavelengths of radiation produced by the Sun and

other sources.

superpose

Wave of the electromagnetic spectrum used for producing images of bones

and tissue.

radio waves

Wave with the highest frequency in the

electromagnetic spectrum.

X-ray

A wave in which the direction of vibration is perpendicular to that of the

wave.

9.


Waves extended question

Microwaves have a frequency range of 300 million Hz to 300 000 million Hz.

They are used both for mobile phones and for cooking food.

In microwave ovens, the microwaves are absorbed by water in food, causing it to warm up. The frequency of microwaves used in ovens is 2500 million Hz.

Mobile phones send and receive use microwaves for communication. These microwaves are not absorbed by water, but they do cause a very small heating effect.

Living cells contain water.

Explain why microwaves from ovens are dangerous but microwaves from mobile phones are thought to be safe for you to use.

Suggest some precautions you should take with your mobile phone. (6 marks)

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Merits awarded

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Waves extended question

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Year 8 – Science Homework Ecosystems keywords


aerobic respiration The substance in blood that carries oxygen around the body.

anaerobic respiration Chemical reaction where glucose reacts with oxygen to release energy, carbon

dioxide, and water.

haemoglobin A lack of minerals, that causes

poor growth.

oxygen debt Chemical containing minerals, normally

applied to soil.

deficiency Extra oxygen required after anaerobic respiration to break down lactic acid.

fermentation Chemical reaction that takes place

without oxygen. Glucose is converted into lactic acid and energy is released.

fertiliser Green pigment in plants and algae which absorbs light energy.

chlorophyll Chemical reaction used by

microorganisms to convert glucose into ethanol, carbon dioxide, and energy.

11.


Ecosystems extended question

Explain, in detail, how plants are adapted for photosynthesis. (6 marks)

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Merits awarded

12.


Ecosystems extended question

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Year 8 – Science Homework Reactions keywords


conservation of mass A chemical reaction in which a

compound breaks down to form simpler compounds and/or elements.

combustion A chemical reaction in which

substances react with oxygen to form oxides.

decomposition A substance that stores energy in a

chemical store which it can release as heat.

exothermic In a chemical reaction, the

total mass of reactants is equal to the total mass of products.

oxidation A reaction that takes in energy, usually

as heat. In other words, it transfers energy from the surroundings.

physical change A chemical reaction in which a

substance reacts quickly with oxygen and gives out light and heat.

fuel A change that is reversible, in which new substances are not made. Examples of physical changes include changes of

state, and dissolving.

endothermic A reaction that gives out energy, usually as heat or light. In other words, it transfers

energy to the surroundings.

13.


Reactions extended question

Look at these energy-level diagrams for melting and freezing.

Identify which graph shows which process.

Explain what each graph shows about how heat is being transferred in the reaction, and explain what is happening in terms of bond breaking and/or bond making. (6 marks)

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Merits awarded

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Reactions extended question

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Year 8 – Science Homework Energy keywords


conduction

The transfer of energy as a wave.

convection

A type of machine which is a rigid bar

that pivots about a point.

radiation

The store containing energy due to the vibration or movement of

particles of a substance.

lever

Transfer of thermal energy when

particles in a heated fluid rise.

pulley

Transfer of thermal energy by the

vibration of particles.

thermal energy store

Radiation given off by the Sun and other objects that brings about

energy transfer.

(thermal) insulator

Material that only allows heat to

travel slowly through it.

infrared (radiation)

A system to lift (or lower) heavy objects.

15.


Energy extended question

The diagram shows a section of roof insulation. The material consists of a layer of foil and a layer of foam on a wooden board.

Explain how the material has been designed to reduce the transfer of thermal energy by conduction, convection, and radiation.

Your answer should include:

description of thermal energy transfers

descriptions of how thermal energy transfer can be reduced.

(6 marks)

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Merits awarded

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Energy extended question

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Year 8 – Science Homework Earth keywords


atmosphere

The gradual increase in the average surface temperature of the Earth.

greenhouse gases

Summarises how carbon and its compounds enter and leave the

atmosphere.

global warming

The mixture of gases surrounding the

Earth.

carbon cycle

A gas that contributes to the greenhouse

effect, such as carbon dioxide.

minerals

Using electricity to split up a compound

into its elements.

ore

Collecting and processing a material so that

it can be used again.

electrolysis

Chemicals that rocks are made from.

recycling

A naturally occurring rock that contains enough of a mineral to make it worth getting the

mineral – and then the metal it includes – out of the rock.

17.


Earth extended question

Describe the sources of human-produced global warming. Suggest ways in which changes in human behaviour may reduce global warming and the consumption of natural resources. (6 marks)

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Merits awarded

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Earth extended question

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Year 8 – Science Homework Genes keywords


chromosome A technique in which scientists

insert foreign genes into organisms to change their characteristics.

genetic modification Section of DNA that contains the information for a characteristic.

allele Long strand of DNA, which contains

many genes.

DNA Process by which the organisms with the characteristics that are most suited to the

environment survive and reproduce, passing on their genes.

gene Different forms of a gene.

mutation When no more individuals of a species remain anywhere in the world.

natural selection Change to DNA that can cause

disease.

extinct Chemical that contains all the information needed to make

an organism.

19.


Genes extended question

Explain how a lack of biodiversity can affect an ecosystem and why helping to preserve biodiversity can benefit humans. (6 marks)

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Merits awarded

20.


Genes extended question

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Wind turbine variables

What was the independent variable in the investigation?

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What was the dependant variable in the investigation?

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State one control variable for the investigation.

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Number of blades



Merits awarded Extension Task:

Research the advantages and disadvantages of using wind turbines to generate electricity.

Number of blades

21.


Wind turbine variables

Explain the advantage of taking repeat readings.

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Extension

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Solar panel variables

A student was investigating how the angle of tilt of a solar panel affected the energy generated by the solar panels.




Research the advantages and disadvantages of solar panels.

22.


Solar panel variables

1. State the independent variable for the student’s investigation.

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2. State one control variable for the student’s investigation.

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3. Describe the trends shown in the table of results.

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Extension

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Variables

For each of the experiments show state the independent, dependent and control variables.

Do earthworms prefer wet or dry soil?

1. You have a tub filled with soil.

2. One half is wet and the other is dry.

3. You put 10 earthworms in the tub and leave them for 1 day.

4. You count how many worms are on the dry side and how many are on the wet side.

Do bananas go brown more quickly if you keep them in the dark or in the light?

1. You have 2 bananas you bought at the same time from the same bunch.

2. You put one banana in a cupboard and the other on a windowsill.

3. You leave them for 3 days and compare bananas to see which is darker.




Invent your own experiment, state the independent, dependent and control variables

23.


Variables

Which object falls more quickly?

1. You have a fork, a hairbrush and a shoe.

2. You drop them out the window at your house

3. You time how long they take to hit the ground.

Which is the best biscuit for dunking?

1. You have 3 types of biscuit; Rich Tea, Custard Creams and Chocolate digestives.

2. You dunk each biscuit into a cup of tea

3. You time how long it takes for each biscuit to break in half.

4. The biscuit that takes the longest to break is the best for dunking.

Experiment

Independent Dependent Control

Worms

Bananas

Objects

Biscuits


Washing powder experiment

Two pupils were given a sample of ‘biological’ washing powder and a sample of ‘non biological’ washing powder.

They investigated how the two powders compare in removing egg-stains from cloth.

Plan

We put ‘biological’ powder into one bowl and ‘non-biological’ powder into the other bowl. We added water.

. We put some egg-stained cloth into each bowl.

. We left the bowls for 30 minutes. We dried out the cloth and saw what happened.




Research the difference between biological and non-biological washing powder.

24.


Washing powder experiment

Look at their report.

(a) Give one way they made their investigation fair. ____________________________________________________

1 mark

(b) Give two ways they could improve their investigation.

1 _______________________________________________________ 1 mark

2 _______________________________________________________ 1 mark

(c) What should they observe to compare the two types of washing powder?

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Modified plants experiment

Scientists at the University of Leeds have found a way to modify the genes of flowering plants. They claim that flowers from modified plants remain fresh in a vase of water for up to six months longer than flowers from unmodified plants.

Plan an investigation you could carry out in the school laboratory to test the claim that flowers from modified plants last for much longer than flowers from unmodified plants.

You will be provided with flowers from modified plants and from unmodified plants.




Research the advantages and disadvantages of genetically modified crop plants.

25.


Modified plants experiment

In your plan give:

• the one factor you will change as you carry out your investigation; (This is the independent variable.)

• the factor you will measure; (This is the dependent variable.)

• one of the factors you should control to ensure a fair test; • the time scale for the investigation.

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Spring extension variables

1. What has the student missed out from their graph?




Research “Hooke’s law”

26.


Spring extension variables

2. State the independent variable for the student’s investigation.

3. State the dependent variable for the student’s investigation.

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4. State one control variable for the student’s investigation.

Extension

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Photosynthesis graph




Research factors that can affect the rate of photosynthesis.

27.


Photosynthesis graph

Describe the trend shown in the graph.

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Extension

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Hydrocarbon graph

Plot the results in the table on the graph.

Draw an appropriate line of best fit.




Research hydrocarbons.

28.


Hydrocarbon graph

One of the points is anomalous.

Draw a ring around the anomalous point on your graph.

Extension

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Limestone experiment

A student investigated what happens when limestone is heated strongly.

This is the method the student used:

• measure the mass of limestone before heating

• measure the mass of solid product after heating

• repeat the experiment three more times.

The student’s results are shown in the table below.

State one control variable for the student’s investigation

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Research the uses of limestone.

29.


Limestone experiment

Calculate the average (mean) mass lost. Show your working and don’t forget units

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Mean mass lost: _____________________

Suggest a possible reason for the student obtaining different results each time

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Extension

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Line and bar graphs

Draw a graph for each of the tables below, you will need to decide whether to draw a bar chart or line graph.

Graph 1 Graph 2

Car colour Number of cars

Red 15

Black 19

Silver 10

Yellow 1

Blue 6

Time (minutes) Distance (m)

0 0

15 12

30 24

45 35

60 49




Describe the trend on each graph.

30.


Line and bar graphs

Graph 3

Extension

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Time (sec)

Temperature (oC)

0 45

45 20

90 5

135 2

180 1

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Carbon dioxide graph

Plot a graph of the student’s results on the grid below. Label the x axis and draw a line of best fit.

Time in minutes Volume of carbon dioxide collected in

cm3

0 0

1 46

2 70

3 85

4 94

5 96

6 96

7 96




Describe what an anomaly is.

31.


Carbon dioxide graph

Extension

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Year 8 - Science Homework

pH graph

Draw a line graph for the results shown.

What would be the likely pH of the solution if the pupil added a further 2 cm3 of alkali solution?

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volume of alkali added (cm3)

pH of resulting mixture

0.0 5.0

2.0 5.0

4.0 5.0

6.0 5.5

8.0 6.0

10.0 7.0

12.0 8.0

14.0 8.5

16.0 9.0

18.0 9.0

20.0 9.0




Research how knowledge of acids and alkalis can help treat wasp and bee stings

32.

Year 8 - Science Homework

pH graph

Extension

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Temperature graph

Draw a graph for the results.

Draw a smooth curve of best fit.

From your curve, estimate the temperature of the water after three minutes.

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Time (minutes) Temperature (ºC)

0.0 20

0.5 26

1.0 31

1.5 36

2.0 41

2.5 46

3.0

3.5 57

4.0 56

4.5 58

5.0 59




Research what the “resolution “ of a scientific instrument is.

33.


Temperature graph

Extension

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Oxygen bubbles experiment



Merits awarded

34.


Oxygen bubbles experiment

Explain why it is a good idea to take repeat readings for an experiment.

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Calculate the mean number of bubbles released per minute when the lamp was 40 cm

from the pondweed.

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Mean number of bubbles at 40 cm = __________________

Plot the results on a line graph.

Describe the trend shown in the graph.

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State the independent variable for the investigation

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State the dependent variable for the investigation

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Hair dye experiment

Jason wanted to find out if hair dye makes hair weaker. He used 5 hairs of equal length. He soaked each hair in a different concentration of hair dye for 15 minutes. He added masses to each hair until it broke.




List the control variables for the experiment

35.


Hair dye experiment

(a) The table below shows Jason’s results.

(i) Plot a graph of Jason’s results and draw a line of best fit.

concentration of hair dye

(%)

mass needed to break the hair

(g)

0.4 71

0.8 67

1.2 64

1.6 61

2.0 58

(ii) Use the graph to work out the mass needed to break hair soaked in water (0% hair dye).

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(b) What was the independent variable that Jason changed in this experiment?

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(c) What was the dependent variable that Jason measured in this experiment?


Hair dye experiment

(d) What is the relationship between the concentration of hair dye and the mass needed to break the hair?

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(e) Jason wanted to investigate whether soaking hair in dye for different amounts of time affected the strength of the hair. Jason drew a table for his results. Add headings and units to the table below for Jason’s investigation.

........................................ (..........) ………………………………………… (..........)

Extension

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36.


Pollen grain experiment

Amy and Tom investigated how sugar affects the growth of pollen grains. They looked at pollen grains under a microscope.




Write some clear instructions for writing a good plan.

37.



(a) Give two ways in which Tom’s plan is better than Amy’s plan.

1 _________________________________________________________

2

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(b) In Tom’s investigation, what factor did he change (the independent variable)?

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(c) Look at Tom’s results in the table below.

concentration of sugar solution (%)

percentage of pollen grains that had started to grow (%)

0 0

5 30

10 100

15 30

20 10

25 0

He plotted five of his results on graph paper.



Plot the result for 20% sugar solution.

(d) Tom’s conclusion was, ‘The greater the concentration of sugar solution, the greater the percentage of pollen grains that had grown.’

Do his results support his conclusion? Tick one box.

yes no

Use the results in the graph to explain your answer. ___________________________________________________________

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38.

crown hills community college year 8 science homework

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