lime (calcium oxide) is used in agriculture to reduce the...

Q1. Lime (calcium oxide) is used in agriculture to reduce the acidity of soils.

Describe, as fully as you can, the reaction by which lime is made.

Name any other product(s).

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

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

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

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

............................................................................................................................................... (Total 3 marks)

Q2. Portland cement was invented by Joseph Aspdin, a builder from Leeds. The flow diagram shows how cement is made.

(a) (i) Name the raw material X used to make cement.

.......................................................................................................................... (1)

(ii) In the kiln the raw materials are heated to about 1500°C. The limestone (calcium carbonate) is broken down at this temperature. Complete the word equation for this reaction.

calcium carbonate → ........................................ + carbon dioxide (1)

(iii) Suggest one major cost of this process other than the cost of the raw materials.

.......................................................................................................................... (1)

(b) Cement can be used to make concrete. Name two substances that must be mixed with cement to make concrete.

1 .....................................................................

2 ..................................................................... (2)

(Total 5 marks)

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Q3. Portland cement was invented by Joseph Aspdin, a builder from Leeds. The flow diagram shows how cement is made.

(a) What are the two raw materials used to make cement?

1 .....................................................................

2 ..................................................................... (1)

(b) Cement is mixed with three substances to make concrete. Choose from the list the three substances used.

crushed rock iron ore quicklime sand

slag soda water

1 .....................................................................

2 .....................................................................

3 ..................................................................... (3)

(Total 4 marks)

Q4. Limestone is an important raw material.

The diagram shows a lime kiln. The limestone is heated by the burning coal.

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(i) Suggest why hot air is blown into the lime kiln.

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

..................................................................................................................................... (1)

(ii) Give two reasons why carbon dioxide is produced in the lime kiln.

Reason 1 .....................................................................................................................

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

Reason 2 .....................................................................................................................

..................................................................................................................................... (2)

(Total 3 marks)

Q5. Limestone is an important raw material.

(a) The main compound in limestone has the formula CaCO3 .

Name the elements in this compound.

1 .................................................................................................................................

2 .................................................................................................................................

3 ................................................................................................................................. (2)

(b) Limestone has many uses. Select from the list below two important materials made from limestone.

cement diesel oil glass

poly(ethene) sodium hydroxide sulphuric acid

.............................................................. and .............................................................. (2)

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(c) The diagram shows a lime kiln. The limestone is heated by the burning coal.

(i) Suggest why hot air is blown into the lime kiln.

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

............................................................................................................................ (1)

(ii) Give two reasons why carbon dioxide is produced in the lime kiln.

Reason 1 ............................................................................................................

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

Reason 2 ............................................................................................................

............................................................................................................................ (2)

(d) (i) Quicklime (calcium oxide) can be converted to slaked lime (calcium hydroxide) by adding water. Write a word equation to represent this reaction.

...................................... + ...................................... → .................................... (1)

(ii) Why do farmers sometimes add slaked lime to acidic soil?

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

........................................................................................................................... (1)

(Total 9 marks)

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Q6. An old lime kiln made in the ground is shown.

(a) The thermal decomposition of calcium carbonate makes a white solid and carbon dioxide.

(i) Name a naturally occurring form of calcium carbonate.

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

........................................................................................................................... (1)

(ii) What does thermal decomposition mean?

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

........................................................................................................................... (2)

(iii) Suggest and explain the purpose of the coal.

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

........................................................................................................................... (2)

(iv) Write a word equation for the thermal decomposition of calcium carbonate.

................................... → ................................... + .................................... (2)

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(b) The diagrams show what happens when drops of cold water are added to the white solid formed by heating calcium carbonate.

(ii) What type of chemical reaction takes place?

........................................................................................................................... (1)

(ii) Give the chemical name of the solid formed. Give a use of this solid.

Name ................................................................................................................

Use ................................................................................................................... (2)

(Total 10 marks)

Q7. Sea water contains magnesium ions. Magnesium oxide can be obtained from sea water using the following process.

(a) State the chemical name for limestone.

.................................................................................................................................... (1)

(b) Write a word equation for the action of heat on limestone.

.................................................................................................................................... (2)

(c) State the chemical name for slaked lime.

.................................................................................................................................... (1)

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(d) Write a balanced chemical equation for the addition of water to quicklime.

................................................................................................................................... (2)

(e) How can magnesium hydroxide be separated from sea water?

................................................................................................................................... (1)

(f) Suggest and explain how magnesium could be obtained from magnesium oxide.

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

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

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

................................................................................................................................... (2)

(Total 9 marks)

Q8. Magnesium chloride is a useful salt. The flow diagram shows how it can be made.

(i) Describe how calcium hydroxide can be made from limestone.

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

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

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

..................................................................................................................................... (2)

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(ii) Write a word equation for the neutralisation of magnesium hydroxide with a suitable acid to form magnesium chloride.

..................................................................................................................................... (2)

(Total 4 marks)

Q9. Bags of readi-to-mix concrete contain three ingredients.

Complete each sentence by choosing the correct words from the box.

Cement is made by heating.......................................... and ......................................... in a rotary kiln.

To make concrete, the contents of the bag of readi-to-mix concrete must be mixed with

............................................................................... . (Total 3 marks)

Readi-to-mix Concrete

contains cement

crushed rock sand

clay limestone salt slaked lime water

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Q10. Limestone contains the compound calcium carbonate, CaCO3.

(a) Limestone is used to make cement in a rotary kiln.

Use the information in the diagram to name the two main waste gases from this rotary kiln.

1 .................................................................................................................................

2 ................................................................................................................................. (2)

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(b) Columns used as supports for buildings can be made from materials such as limestone blocks or concrete.

From the diagrams, name which you think is the better material for making a column.

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

Give three advantages for your choice of material.

1 .................................................................................................................................

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

2 .................................................................................................................................

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3 .................................................................................................................................

.................................................................................................................................... (3)

(Total 5 marks)

Q11. Limestone contains calcium carbonate.

(a) Calcium carbonate has the formula CaCO3.

Complete the sentence by writing in the correct numbers.

The formula of calcium carbonate is made up of 1 calcium atom, ............ carbon atom(s)

and ............ oxygen atom(s). (2)

(b) When limestone is heated it forms two other compounds.

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(i) State one safety precaution that you should take when heating limestone.

........................................................................................................................... (1)

(ii) Name the white solid produced.

........................................................................................................................... (1)

(iii) Why does a piece of limestone lose mass as it is heated?

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

........................................................................................................................... (1)

(d) A company wants to quarry limestone. There are some houses near the quarry.

Residents in the houses say that they do not want a quarry next to them.

(i) Suggest two reasons why they do not want the quarry next to them.

1 ........................................................................................................................

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

2 ........................................................................................................................

........................................................................................................................... (2)

(ii) Suggest one possible benefit to the residents of having a quarry near their houses.

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

........................................................................................................................... (1)

(Total 8 marks)

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Q12. Limestone is mainly calcium carbonate.

(a) Quicklime is produced by heating limestone.

(i) Complete the word equation for this reaction by writing the chemical name of the solid and the gas produced.

calcium carbonate → ................................. + ................................. . (2)

(ii) What is the name for this type of chemical reaction?

.......................................................................................................................... (1)

(b) Quicklime is used in self-heating cans.

The diagram shows a self-heating can designed to raise the temperature of coffee to 60 °C.

The button on the base of the can is pushed. The foil separator breaks, allowing water to mix with the quicklime. After about 3 minutes, the can is opened by the ring pull. Insulating materials are used inside the walls of the can to prevent either the lips or the fingers from being burned.

(i) Explain why the coffee becomes hot.

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

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

.......................................................................................................................... (2)

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(ii) Suggest two reasons why it is not possible to re-use this self-heating can.

1 .......................................................................................................................

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

2 .......................................................................................................................

.......................................................................................................................... (2)

(Total 7 marks)

Q13. (a) Limestone is a hard rock that is used as a building material. Limestone was used by the Egyptians to make plaster.

Reaction 1 – calcium carbonate, CaCO3, was decomposed by heating limestone

CaCO3 → CaO + CO

2

Reaction 2 – water was added to the solid produced to make slaked lime

CaO + H2O → Ca(OH)

2

Reaction 3 – a mixture of slaked lime and water was used as plaster. After the plaster had set it became even harder with age

Ca(OH)2 + CO

2 → CaCO

3 + H

2O

(i) Name the solid formed when calcium carbonate decomposed.

........................................................................................................................... (1)

(ii) Use the reactions to explain how the plaster became even harder with age.

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(b) A gardener wanted to make a step up to his greenhouse door. He decided to use a mixture of cement and sand to make mortar.

He experimented using mixtures with different cement to sand ratios.

• The mortar mixtures were put in the same sized mould.

• Each mortar mixture was allowed to set hard.

• He then dropped a metal ball from increasing heights until the set mortar cracked.

• He recorded his results in a table.

(i) What is the relationship between the volume of sand and the strength of the mortar?

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

........................................................................................................................... (1)

Volume of sand

in cm3 Volume of cement

in cm3

Height the metal ball dropped to crack the set

mortar in cm

800 100 17

700 100 24

600 100 30

500 100 36

400 100 37

300 100 48

200 100 54

(ii) The gardener was not sure about some of his results.

Use the results to explain why.

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........................................................................................................................... (2)

(Total 7 marks)

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Q14. A limestone quarry is in an area of natural beauty and near several villages. The company operating the quarry wants planning permission to build a new cement works in the quarry.

The diagram shows some of the substances used and produced at a cement works.

(a) Limestone is mainly calcium carbonate, CaCO3.

Write the correct number in the box to complete each sentence.

(i) The formula shows that calcium carbonate, CaCO3,

contains different elements. (1)

(ii) Calcium carbonate, CaCO3, contains a total number of atoms.

(1)

(b) The company wants the new cement works because the nearest cement works is 100 km from the quarry. The company argues that a new cement works sited inside the quarry would reduce carbon dioxide emissions.

Suggest why the new cement works might reduce carbon dioxide emissions.

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

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

..................................................................................................................................... (1)

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(c) Residents from the villages near the quarry are concerned that there will be atmospheric pollution from the new cement works.

(i) Name and explain how one of the emissions from the chimney causes atmospheric pollution.

Name of emission: ...........................................................................................

Explanation: .....................................................................................................

........................................................................................................................... (2)

(ii) Suggest what the company could do to reduce this atmospheric pollution.

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

........................................................................................................................... (1)

(Total 6 marks)

Q15. Limestone contains calcium carbonate, CaCO3.

At a cement works, limestone is mixed with clay and heated in a kiln.

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(a) (i) When methane is burned in this process the waste gases contain carbon dioxide and nitrogen.

Explain why.

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

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

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

........................................................................................................................... (2)

(ii) Complete the symbol equation for the thermal decomposition of calcium carbonate.

CaCO3 → ......................... + .........................

(2)

(b) A different fuel is burnt at the cement works.

Suggest one reason the company may give for using this different fuel at the cement works.

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

..................................................................................................................................... (1)

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(c) The cement works continue to burn the different fuel.

Local residents are concerned because more children are suffering asthma attacks. Residents have also noticed that parked cars are becoming dirty because of smoke particles from the chimney.

The table shows the possible medical risk from smoke particles.

It is also recommended that to avoid damage to health, the concentration of any particles should be no higher than 2 parts per million (ppm).

Scientists were brought in to monitor the emissions from the cement work’s chimney. They positioned four sensors around the cement works to monitor airborne smoke particles.

Particle size in mm Medical effect

Larger than 0.4 No medical risks known

0.3 and smaller Causes asthma attacks

0.2 and smaller May cause cancer

These four sensors only detect particle sizes larger than 0.5 mm and measure the concentration of particles in ppm. The scientists reported that the particle sensors showed that the average concentration of particles was 1.8 ppm. The scientists concluded that there was no risk to health.

(i) Explain why the local residents objected to the positions of the four sensors.

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........................................................................................................................... (2)

(ii) What evidence did the scientists use to conclude that there was no risk to health?

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........................................................................................................................... (1)

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(iii) The local residents were still concerned that there was a risk to health, even though the average concentration of particles was 1.8 ppm.

Explain why.

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........................................................................................................................... (3)

(Total 11 marks)

Q16. Limestone has been called the Earth’s most useful rock.

(a) Limestone contains calcium carbonate, CaCO3.

(i) Complete the table to show the number of atoms of each element in the formula of calcium carbonate.

Calcium has been done for you.

(2)

Element Number of atoms in the formula CaCO3

Calcium, Ca 1

Carbon, C

Oxygen, O

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(ii) The diagram below represents a carbon atom.

Use words from the box to label the parts of this atom.

(2)

bond electron molecule nucleus

(b) At a cement works, limestone is mixed with clay and heated in a kiln.

Use the information in the diagram to answer these questions.

(i) Name the fuel that is used to heat the limestone and clay.

........................................................................................................................... (1)

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(ii) Limestone contains calcium carbonate, CaCO3.

Draw a ring around the correct gas in the box to complete the sentence.

(1)

The gas formed when calcium carbonate decomposes is

argon.

carbon dioxide.

nitrogen.

(c) The cement works starts to burn a different fuel.

Local residents are concerned because more children are suffering asthma attacks. Residents have also noticed that parked cars are becoming dirty because of smoke particles from the chimney.

The table shows the possible medical risk from smoke particles.

Particle size in mm Medical effect

Larger than 0.4 No medical risks known

0.3 and smaller Causes asthma attacks

0.2 and smaller May cause cancer

(i) Give two reasons why local residents are concerned about the cement works burning a different fuel.

1 ........................................................................................................................

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

2 ........................................................................................................................

........................................................................................................................... (2)

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(ii) The company operating the cement works stated that smoke particles from the chimney had not changed since it started burning the different fuel.

If you were a local resident, what evidence would you like to see to help you decide if the company’s statement is true or not?

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

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

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

........................................................................................................................... (2)

(Total 10 marks)

Q17. Limestone contains calcium carbonate, CaCO3

(a) The flow chart shows the stages in the limestone cycle.

Write the name of the correct calcium compound in each empty box to complete the flow chart.

(3)

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(b) Limestone is heated with clay to make cement. Cement is mixed with sand to make mortar.

A student investigated the strength of six mortar mixtures. Each mortar mixture contained 100cm3 cement but each contained a different volume of sand.

To do the investigation the student:

• added and stirred water into each mortar mixture

• put each mixture into the same sized moulds

• left each mixture to set hard

• dropped a metal ball from increasing heights until the mortar cracked

• recorded the results in a table.

Volume of sand in cm3

Volume of cement in cm3 Height the metal ball was

dropped from to crack the mortar in cm

700 100 24

600 100 30

500 100 36

400 100 37

300 100 48

200 100 54

(i) What happens to the strength of the mortar as the volume of sand increases?

............................................................................................................... (1)

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(ii) The student was worried about an anomalous result.

Which result was anomalous?

Volume of sand = ................. cm3

Explain why you have chosen this result.

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

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

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

............................................................................................................... (2)

(c) The student repeated the investigation but used six concrete mixtures.

From the results the student concluded correctly that concrete was stronger than mortar.

Suggest one reason why concrete is stronger than mortar.

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

........................................................................................................................ (1)

(Total 7 marks)

Q18. Limestone and the products of limestone have many uses.

(a) Limestone is quarried.

Photograph © Lonny Kalfus / Getty Images

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Quarrying limestone has impacts that cause environmental problems.

Tick ( ) two impacts that cause environmental problems.

(2)

Impact of quarrying Tick ( )

Puts off tourists

Causes dust pollution

Increases jobs

Increases traffic

(b) Limestone contains calcium carbonate, CaCO3. When it is heated calcium carbonate

produces calcium oxide and carbon dioxide.

The word equation for this reaction is:

calcium carbonate → calcium oxide + carbon dioxide

(i) Complete the sentence.

The reaction when calcium carbonate is heated is called

thermal ........................................... (1)

(ii) 100 g of calcium carbonate was heated and produced 56 g of calcium oxide. Calculate the mass of carbon dioxide produced.

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

....................................... g (1)

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(c) The flow chart shows the stages in the limestone cycle.

Complete the names of the calcium compounds formed in the flow chart.

(2)

(Total 6 marks)

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##

from limestone/marble; from calcium carbonate; action of heat/thermal decomposition; (other product is) carbon dioxide

any three for 1 mark each [3]

-

M2. (a) (i) clay

for one mark

(ii) calcium oxide / quicklime / CaO for one mark

(iii) sensible answers such as cost of fuel etc. / accept a wide range of appropriate answers

for one mark 3

(b) sand gravel (owtte) e.g. crushed rock water

any two for 1 mark each 2

[5]

M3. (a) limestone clay

both for 1 mark 1

(b) water sand crushed rock

for 1 mark each 1

[4]

M4. (i) (hot air) gives faster reaction makes coal burn faster (provides air / oxygen to help to) allow the coal to burn / helps combustion flushes out the waste / gases / carbon dioxide

any one for 1 mark 1

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(ii) decomposition of limestone yields carbon dioxide (owtte) the combustion / burning of coal produces carbon dioxide (owtte)

each for 1 mark 2

[3]

M5. (a) calcium carbon oxygen

2 correct for 1 mark 3 correct for 2 marks

2

(b) cement glass

each for 1 mark 2

(c) (i) allows coal to bum / flushes out CO2

for 1 mark 1

(ii) produced by burning coal produced by decomposition of limestone

each for 1 mark 2

(d) (i) calcium oxide + water → calcium hydroxide or quicklime + water → slaked lime

for 1 mark (allow composite equation from these two)

1

(ii) to neutralise it / because it is alkaline or basic for 1 mark

1 [9]

M6. (a) (i) limestone / chalk / marble 1

(ii) breakdown / splits up 1

with heat 1

(iii) to burn / react with air / oxygen 1

release energy / heat / exothermic / keeps temperature high 1

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(iv) calcium carbonate → calcium oxide + carbon dioxide

calcium oxide 1

correct equation 1

(b) (i) exothermic / slaking / hydration not hydrolysis

1

(ii) calcium hydroxide / slaked line 1

mortar / neutralise acidity in soil / neutralise acid lake water / soften hard water / to make cement

not in agriculture not to make lime water

1 [10]

M7. (a) calcium carbonate

not formula 1

(b) calcium carbonate → calcium oxide not common names allow correct formulae

1

+ carbon dioxide 1

(c) calcium hydroxide not formula

1

(d) CaO + H2O → Ca(OH)

2

allow if doubled

all formulae correct, no extra ones 1

balanced 1

(e) filtration allow centrifugation

not decanting not evaporation, crystallisation

1

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(f) electrolysis stated or implied

molten MgO / magnesium oxide is ionic / Mg2+ goes to cathode

not just heated 1

or add sodium / K / Ca / Li / a more reactive metal 1

displaces Mg / reduces Mg give no marks if reference made to reduction by C or H

1 [9]

M8. (a) (i) heat (the limestone)

accept decompose limestone accept heat with coke

1

add water / slake

dependent on 1st mark unless they say add water to the calcium oxide

1

(ii) magnesium hydroxide + hydrochloric acid

1

→ magnesium chloride + water / H2O

1 mark for each side of the equation (if a symbol equation is given then give 1 mark for correct formulae (all) and 1 mark for balancing)

1 [4]

M9. clay 1

limestone 1

water 1

[3]

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M10. (a) any two from:

• nitrogen accept formulae N / N

2

• carbon dioxide accept formula CO

2

ignore CO

• water (vapour) / steam accept formula H

2O

2

(b) any three from:

no mark for ‘limestone’ or ‘concrete’ on first line – mark advantages only

limestone

• abundant / local ignore ideas of speed of production or easier to use

• natural material or no ‘processing’ needed

• relatively easy to cut

• appearance better

concrete

• raw materials are abundant

• can be reinforced (by steel rods) / strong(er) / supported (by steel rods) accept ‘can build higher’

• concrete mixture can be poured / moulded / constructed on site

• less reactive with acid rain / weathering / erosion ignore density / extraction / quarrying / pollution / cost

3 [5]

M11. (a) 1 / one 1

3 / three 1

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(b) (i) (wear safety) glasses / masks / gloves accept do not handle hot objects / use tongs or accept other safety points such as, ‘tie hair back’

1

(ii) calcium oxide accept quicklime

1

(iii) carbon dioxide / CO2 is given off

accept a gas is given off 1

(d) (i) any two from:

• dust / atmospheric pollution

• noise

• eyesore

• destroys habitats

• (extra) traffic

• any other named pollution or description of pollution 2

(ii) any one from:

• employment

• increases local trade / makes money

• future development of quarry recreation / park / lake / reservoir do not accept cheaper houses / land / new roads

1 [8]

M12. (a) (i) calcium oxide / CaO 1

carbon dioxide / CO2

products can be in either order ignore chemical names other than calcium oxide or carbon dioxide

1

(ii) (thermal) decomposition accept endothermic

1

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(b) (i) (chemical) reaction / react accept calcium hydroxide / slaked lime produced ignore incorrect products

1

energy / heat released / exothermic ignore gets hot / heats up if neither mark awarded then allow ‘mixing the chemicals heats up the coffee’ for 1 mark

1

(ii) any two from:

• foil has been broken(*)

• ring pull used(*) (*)if neither mark awarded accept ‘cannot / difficult to repair’ for 1 mark ignore button pushed

• quicklime and / or water mixed / reacted accept reaction not reversible accept cannot / difficult to replace quicklime / water / chemicals

2 [7]

M13. (a) (i) calcium oxide / quicklime

allow calcium monoxide do not accept calcium dioxide ignore chemical formulae

1

(ii) any three from:

• carbon dioxide / CO2

• (carbon dioxide) reacts (with the calcium hydroxide / slaked lime / plaster) allow reaction 3 identified do not allow incorrect reaction ignore mixes, unless they state the correct product

• limestone / calcium carbonate / CaCO3 forms

allow marble / chalk

• water is lost / evaporates it = plaster allow moisture ignore dries

3

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(b) (i) as the amount / volume of sand decreases the strength of the mortar increases

accept as sand decreases the mortar is stronger / harder to crack allow as sand decreases the mortar increases allow converse ignore references to height of metal ball

1

(ii) any two from:

• 400 / 5th result is anomalous

accept two results (36 and 37 / 400 and 500 / 4th and 5th) are almost the same accept result at 400 should be 42

• the interval between the others is similar or the interval is about 6/7 allow the other results fit a pattern / are on a straight line

• he has only one set of results allow he has only done it once ignore reliable

2 [7]

M14. (a) (i) 3 / three 1

(ii) 5 / five 1

(b) any one from:

• less / no transport accept less / no distance

• less / no (fossil) fuel used ignore references to carbon dioxide / carbon emissions

1

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(c) (i) carbon dioxide / CO2

for a correct emission 1

(causes) global warming / climate change / greenhouse gas explanation must be correct for named emission ignore ozone layer

or

(cement) particles / smoke (1)

(causes) asthma / dust / (global) dimming (1) accept breathing problems

or

sulfur dioxide / SO2 / nitrogen oxides / NO

x (1)

(causes) acid rain (1) do not accept nitrogen or water vapour for emissions do not accept no named emission

1

(ii) absorb / trap / capture / filter / pass through water / scrub / electrostatic attraction ignore condense / off setting / different fuel

1 [6]

M15. (a) (i) oxygen / air reacts with carbon / methane (to form carbon dioxide)

accept from the decomposition / reaction of calcium carbonate ignore CO

2 from the air

1

nitrogen is (unreacted) from the air 1

(ii) CaO 1

CO2

any order ignore words any incorrect balancing max 1 mark

1

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(b) any one from:

• more energy / efficient allow converse for present fuel

• from a sustainable / renewable resource

• produces less / no carbon dioxide / greenhouse gases / global warming ignore no pollution / environmental damage

• more profit or money for local economy

accept fuel is cheap(er)

• more readily available it = different fuel

1

(c) (i) any two from:

• not near where people / residents live accept not between cement works and where people live ignore sensors are unsightly

• not positioned where concentration of particles was likely to be highest

• not positioned downwind 2

(ii) the average / concentration was 1.8(ppm) or the average / concentration was below 2(ppm)

accept 1.8(ppm) is less than 2.0 (ppm) 1

(iii) any three from:

• children / people suffering asthma attacks

• result was an average

• readings (at some (2/3) sensors) could have been higher than 2ppm

• sensors did not detect particles below 0.5mm

• small particles / particles below 0.5mm / 0.4mm / 0.3mm / 0.2mm could (still) cause cancer / asthma ignore global dimming or cars becoming dirty or position of sensors

3 [11]

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M16. (a) (i) 1 1

3 1

(ii) nucleus 1

electron 1

(b) (i) methane / CH4

accept natural gas ignore air do not allow other gases

1

(ii) carbon dioxide 1

(c) (i) any two from:

• medical risks

• asthma

• cancer

• dirt

• causes global warming / global dimming / greenhouse effect / acid rain ignore death accept effect on health accept difficulty breathing/ lung disease allow smoke particles allow harmful for the environment

2

(ii) any two from:

• have a test done / scientific evidence

• independent (evidence)

• comparison of smoke particles / when different fuels used

• medical evidence or more / less asthma attacks or cancer or dirt on cars

2 [10]

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M17. (a) calcium oxide 1

calcium hydroxide 1

calcium carbonate 1

substances must be in the order shown

(b) (i) strength of mortar decreases (as volume of sand increases) 1

(ii) 400 (cm3)

1

because the height the metal ball dropped from should be 42 cm and not 37 cm

accept because the other results show that the height the metal ball dropped from should have an interval of 6cm

1

(c) contains aggregate allow bonding is stronger

1 [7]

M18. (a) causes dust pollution 1

increases traffic 1

(b) (i) decomposition 1

(ii) 44(g) 1

(c) (calcium) hydroxide 1

(calcium) carbonate 1

substances must be in the order shown [6]

of 39

lime (calcium oxide) is used in agriculture to reduce the...

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