Moza Bint Mohammed Preparatory Independent School for GirlsScience Department

الوطنية االختباراتالعلوم في بنجاح

GRADE 8INDEX

UNIT NO

UNIT NAME CS NO PAGE NO

HOLT SCIENCE AND TECHNOLOGY (PHYSICAL SCIENCE)

8M.3 Uses of Metals 8.13.8,8.13.9,8.13.10,8.13.12 ------------8M.4 Salts 8.14.1,8.14.3 -------------8P.3 Heat and

Temperature8.17.1,8.17.2,8.17.3,8.17.4,8.17.5,8.17.6,8.17.7,8.17.8 274-

276,280,281,282-297

8P.4 Light 8.18.1,8.18.2,8.18.3,8.18.4,8.18.5,8.18.6,8.18.7,8.18.9,8.18.10

652,653,644-648,640,654,654-666

HOLT SCIENCE AND TECHNOLOGY (LIFE SCIENCE)

8L.4 Photosynthesis 8.10.1, 8.10.2, 8.10.3,8.10.4 317-318,332-333,300

8L.5 Feeding Relationship

8.5.1, 8.5.2,8.5.3 486,488-489,491-492

Name :……………………….. Class: ………….. Date : …………………..

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GRADE 8: Materials 3USES OF METAL

8.13.8 Know that the ease of extraction of a metal from its ore depends on its position in the reactivity series.

1) Metals above carbon in the reactivity series must be extracted usinga) Electrolysisb) Reductionc) Oxidationd) Native

2) Metals less reactive than carbon can be extracted from their ores bya) Electrolysisb) Reductionc) Oxidationd) Native

3) Some unreactive metals can be found as elements. They are calleda) Electrolysisb) Reductionc) Oxidationd) Native

Q1) What method is most likely to be used to extract the following metals from their ores? Give reasons for your answers.

a) Zinc : ........................................................................................................

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b)Pottasium : ...............................................................................................

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Q2) Explain why only those metals at the bottom of the reactivity series were known 2000 years ago.

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8.13.9 Know that metals are ductile, malleable and good conductors of heat and electricity, and that these physical properties vary from metal to metal.

Q1) We often make metals more useful by giving them additional properties by mixing small quantities of other metals to form alloys.

a. What useful properties can be given to iron by adding:

1) 1% carbon : ..............................................................................................

2) 4% carbon: ...............................................................................................

3) Vanadium: ................................................................................................

4) Chromium: ...............................................................................................

b. What useful properties can be given to aluminium by adding magnesium?

...........................................................................................................................

c. What useful property can be given to tin by adding lead?

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d. What useful properties can be given to copper by adding tin?

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8.13.10 Link the properties and uses of some well-known metals, such as gold, silver, copper, iron and aluminium.

The list below shows some uses for common metals. In each case explain why the metal is appropriate for this use.

a. Aluminium (in alloys): used to make aeroplanes, cooking pans, high voltage electricity cables, window frames, wrapping chocolate.

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b. Copper (in alloys): used to make coins, household electrical wiring, domestic water pipes.

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c. Iron (in steel): used to make car bodies, girders in bridges, and for reinforcing concrete in buildings.

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d.Tin: used for coating mild steel food cans.

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8.13.12 Contrast the physical properties of metallic and non-metallic elements.

Comparison between the physical properties of metals and non-metals Metals Non-metals

Metals are malleable Non-metals are not malleable

Metals are ductile Non-metals are not ductile

Metals are not brittle Non-metals are generally brittle

Metals are strong Non-metals are not strong.

Metals are good conductors of heat and electricity

Other than graphite, which is a form of carbon, all non-metals are bad conductors of heat and electricity

Metals have a good lustre

Most non-metals have poor lustre

Other than mercury, all metals are solids at room temperature

Non-metals can be solids, liquids or gaseous at room temperature

Other than sodium and potassium all metals

Solid non-metals have low melting points

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have high melting points Materials 4

SALTS8.14.1 Know the different reactions by which salts can be made.8.14.3 Name a number of common salts and state their uses.

1) What products are formed when a metal carbonate reacts with an acida) a salt onlyb) a salt and waterc) a salt, water and carbon dioxided) Metal and acid

2)Which acid could be used to make ammonium nitrate (a type of fertiliser)? a) hydrochloric acidb) sulfuric acidc) nitric acidd) Carbonic Acid

3)Which gas is produced when magnesium reacts with hydrochloric acid? a) carbon dioxideb) oxygenc) hydrogend) Nitrogen

Q1) Potassium nitrate is used as a garden fertiliser.a. Name two elements that it contains that are required by plants to

grow.

..............................................................................................................................

b. It is made from potassium hydroxide. Complete the following word equation for the reaction

potassium hydroxide + ...................... potassium nitrate + .....................

c. It can also be made starting from potassium carbonate. Write a similar equation showing the reaction.

.........................................................................................................................

d.The reaction in part C produces a gas. Describe a test to identify the gas.

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………………………………………………………………………………………

FEEDING RELATIONSHIP

8.5.1 Relate changes in numbers of organisms in a habitat to their feeding relationships.

1) In the food relationship where the lion eats the wildebeest, and the wildebeest eats plants ...

1. The lion is the prey and the wildebeest is the predator2. The lion is the predator and the wildebeest is the prey3. The lion is the primary consumer and the wildebeest is the secondary consumer4. The lion is the secondary consumer and the wildebeest is the primary consumer

a) 1 and 3 only b) 1 and 4 only c) 2 and 3 only d) 2and 4 only

2) If there is a shortage of wildebeest in the area, what are some things the lions might do?

1. move to another area to hunt for food2. eat the bark and roots of trees3. hunt for other animals

a) 3only b) 3 and 2 only c) 1 and 3 only d) 1 and 2 only

3) There are more herbivores than carnivores in a food chain because 1. much energy is lost in the transfer of energy from herbivores to

carnivores2. a larger number of herbivores is needed to support a smaller number of

carnivores3. this is the way for the food chain to stay in equilibrium.

a) 1only b) 2 and 3 only c) 1 and 2 only

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d) All of the above

4) When a population of animal 'X' was introduced into the community, the number of lions increased while the number of wildebeest decreased. Animal 'X' could be a …

a) herbivore e.g., zebrab) carnivore that is a predator of wildebeest and lionsc) carnivore that is a predator of wildebeest but a prey of the lionsd) All of the above

5) What is likely to happen to the population of thrushes if the population of voles increases?

a) it will increase

b) it will decrease

c) it will stay the same

8.5.2 Interpret pyramids of numbers and biomass representing the organisms linked in a food chain.

1) An energy pyramid a) is based on the weight of all the members at each trophic level. b) always has the smallest tier at the bottom. c) is one way of depicting the trophic structure of an ecosystem. d) all of the above

2) What can we conclude from this pyramid of numbers?

a) the producer must be very largeb) the producer must be very smallc) the primary consumer must be a carnivore

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Q1) Number of secondary consumer is biggest.In the left-hand column there are descriptions of four food chains. In the right-hand column there are four pyramids of numbers, which are not drawn to scale.

Draw a line from each description to the correct pyramid of numbers

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8.5.3 Explain why toxins increase in concentration along a food chain.

Q1) Scientists measured the concentration of the insecticide DDT in three animals and a microscopic plant called chlamydomonas.

The food chain for these four organisms is shown below.

Chlamydomonas daphnia fish heron

a) Draw a pyramid of numbers for this food chain.

b)The bar chart shows the concentration of DDT in the four organisms.

Give one reason for the difference in the concentration of DDT in these organisms.

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LIGHT

8.18.1 Know that light travels in straight lines and that objects in the path of light cast shadows.

1) During thunder storm, we see lightning before hearing the thunder because

a) We see faster than we hearb) Light travels faster than soundc) Sound cannot travel through the aird) Light travels faster in water than in air

2) Which of the following statements is FALSE?

a) Light can be reflectedb) Light travels in straight linesc) Light can pass through some objectsd) Light travels as fast as sound

Q1)A B

a) On diagram A draw arrows to show how light travels to the boy’s eyes so that he can see:a) the TV b) the light bulb

c) the cat.

b) On diagram B above draw arrows to show how light travels so that:a) the cat can see the boy

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b) the girl can see the cat

.

8.18.3 Represent a ray of light by a line in diagrams showing reflection, refraction and dispersion of light.

8.18.4 Describe how light is reflected at a surface and understand the difference between reflection by rough and smooth surfaces. Know the characteristics of an image formed in a plane mirror. Describe everyday applications of reflection.

1) Which word means the ray 'bouncing off a surface' like ray 1?

a) refractionb) inductionc) transformationd) reflection

2) The image distance of the image is formed by a plane mirror is

a) The same as the object distanceb) Longer than the object distancec) Shorter than the object distanced) The same as the distance of the observer from the mirror

Q1) Aysha shone a ray of light at a mirror as shown below

She measured the angle of reflection for different angles of incidence.Her results are shown below.

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(a) Which angle of reflection was not measured accurately? ………………………..º

(b) How can you tell this from the table?

…………………………………………………………………………………

8.18.5 Describe how light is refracted at a plane surface and describe everyday applications of refraction.

1)When an incident ray of light hits a water or glass surface, most of the light passes through the air-water interface and a little is reflected. Which of the four rays is the refracted ray?

a) ray 4b) ray 2c) ray 1d) ray 3

2) Referaction happens when light passes from

a) a transparent medium to an opaque mediumb) A translucent medium to an opaque mediumc) One opaque medium to another opaque mediumd) One transparent medium to another transparent medium

3) A swimming pool full of water will appear

a) Shallower than it actually isb) As deep as it actually isc) Deeper than it actually is d) Either shallower or deeper than actually is

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(a)James set up a different experiment as shown below.

He measured the angle of refraction for different angles of incidence. His results are shown in the graph.

Use the graph to answer the questions below.

(i) When the angle of refraction is 20º, what is the angle of incidence? …………………………º

(ii) What conclusion could James draw from his graph? Complete the sentence below.

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When light passes from air into glass, the angle of incidence is always ……………………….the angle of refraction.

(c) On diagram 2, draw a line to continue the refracted ray as it leaves the glass block.

8.18.6 Demonstrate how white light can be split into coloured light by refraction and explain examples of dispersion in everyday life (e.g. oil on water, rainbows).8.18.7 Know that objects appear coloured when viewed in white light because some colours are reflected by the object but others are absorbed.8.18.9 Know the effect of superimposing red, green and blue colour filters.8.18.10 Know that red, green and blue light, when superimposed, create white light and apply this knowledge to television screens and to colour vision

1) The reason things appear to be a color is because they ______ that color of light.

a) absorbb) reflectc) project.d) disperse

2)The range of colors we can see is called

a) infra-redb) ultravioletc) the visible spectrumd) X ray

3) The order of colors in the spectrum is

a) ROYGBIVb) VIBGYORc) RGBYOVId) YORVIGB

Q1) Fatima uses different colours of light and different coloured balls.

Complete the table to show the colours that the balls appear to Fatima.

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colour of ball colour of thelight

the colour theball appears to

Naomi

green

w hite red

white

(ii) Why does a black object appear black in any light?

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Q2 ) Two cyclists are riding along a dark road at night. One is wearing black clothes and the other is wearing light-colored clothes.

A car is driving behind the two cyclists. Light from the car headlamp shines on the cyclists.

(a) What happens to the light when it reaches the light-colored clothes?

………………………………………………………………………….

(b) On the drawing above, draw a ray of light to show how light from the headlamp reaches the driver so that he can see the cyclist in the light-colored clothes.Draw arrows to show the direction of the light.

(c) What happens to the light when it reaches the black clothes?

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