Chemistry of the atmosphere part 2 Mark schemes

Q1.

(a) (i) 42 000

correct answer gains 2 marks with or without working

allow 42 kJ

if answer incorrect : correct substitution 500 x 4.2 x 20 gains 1 mark

2

(ii) any two from:

• eye protection

• lab coat

• heat-proof mat

• (heat-proof) gloves

• (long) hair tied back

• stand up

• secure the beaker

2

(iii) Stir the water before measuring the temperature.

1

Place a lid on the beaker.

1

(b) the products → S

1

the activation energy → Q

1

the energy released by the reaction → P

1

(c) carbon dioxide produced

it = propane

allow converse arguments

allow greenhouse gas / global warming / atmospheric pollution

(crude oil / propane) non-renewable

1

allow crude oil running out

1

[11]

Q2.

(a) (i) C7H16

mark answer line first

answer may be given in the table

1

(ii) CnH2n+2

1

(b) (i) carbon monoxide

do not accept carbon oxide

do not accept water

ignore CO

1

(ii) because of partial / incomplete combustion (in reaction 2) or complete combustion (in reaction 1)

allow because there is less / insufficient oxygen (in reaction 2) or sufficient oxygen (in reaction 1) allow different amounts of oxygen used (in the reactions) or 19O2 (in reaction 1) and 13O2 (in reaction 2)

ignore air

1

(c) (i) 15 (%)

ignore units

1

(ii) water (vapour)/steam

allow H2O / OH2 / hydrogen oxide

1

(iii) sulfur in petrol / crude oil (reacts with oxygen)

it = sulfur dioxide

1

(ii) because nitrogen and oxygen (are in the air and) react

allow nitrogen and oxygen burn

accept nitrogen + oxygen → nitrogen oxide or symbol equation

ignore air

1

at high temperature (inside a petrol engine)

allow heat / hot (engine)

1

(d) because carbon dioxide / it causes global warming or

allow because carbon dioxide / it causes greenhouse effect / climate change

1

because carbon dioxide / it has an impact on oceans

because this carbon dioxide / carbon / it was ‘locked up’ (in fossil fuels) or

because the percentage/amount of carbon dioxide / it in the atmosphere is increasing

1

[11]

Q3.

(a) (i) bar drawn between 84 and 86

1

(ii) sulfur dioxide linked to acid rain

1

carbon particles linked to global dimming

1

(b) (i) any one from:

• plants / trees absorb (carbon dioxide)

• coal ‘locks up’ (carbon dioxide)

1

(ii) it increases the amount (of CO2)

1

because carbon in coal (forms carbon dioxide)

accept because carbon / coal burns / reacts with oxygen (to produce CO2)

1

[6]

Q4.

(a) (i) use of carbon throughout = max 1

burning biodiesel releases CO2

ignore burning trees

1

CO2 is absorbed / used by the crops/plants (used to produce the biodiesel)

allow CO2 absorbed / used by trees

1

(ii) allow use of carbon for carbon dioxide throughout

increases CO2 / greenhouse effect

accept causes global warming

OR

allow causes climate change

less CO2is absorbed (from atmosphere)

ignore other correct effects

1

because burning trees releases CO2

accept fewer trees to absorb CO2

or crops / plants do not absorb as much CO2 as trees

OR

because there is less photosynthesis

ignore habitats / biodiversity

if no other mark awarded global dimming because of smoke / particles gains 1 mark

1

(b) any one from:

ignore carbon neutral / cost / less harmful / environmentally friendly

• crude oil / fossil fuel is running out / non-renewable

allow biodiesel is renewable / sustainable

• demand for fuels / energy is increasing

ignore demand for biodiesel is increasing

• new legislation / protocols

1

(c) (i) uses crops / land that could be used for food

allow destroys habitats or reduces biodiversity

ignore cost

1

(ii) increases the cost of food / land

ignore cost of machinery / process

ignore cheaper to produce biodiesel

1

[7]

Q5.

(a) carbon dioxide decreased (by plants / trees)

allow plants / trees absorbed carbon dioxide

1

oxygen increased (by plants / trees)

allow plants / trees released oxygen

if neither of these marks awarded

allow plants / trees

photosynthesise for 1 mark

1

because coal ‘locks up’ / traps / stores carbon dioxide / carbon

allow trees ‘locked up’ carbon dioxide / carbon

1

(b) carbon / C

hydrogen / H

sulfur / S

all 3 correct 2 marks

1 or 2 correct 1 mark

allow H2

ignore oxygen

2

(c) (i) 2 2

balancing must be correct

do not accept changed formulae

1

(ii) increases atmospheric pollution

carbon dioxide / CO2 released

1

from the (thermal) decomposition of calcium carbonate or

accept causes global warming or CO2 is a greenhouse gas

description of this decomposition or equation

ignore sulfur dioxide and effects in this part

1

decreases atmospheric pollution

sulfur dioxide / SO2 is removed

accept less acid rain produced

1

by reaction with calcium oxide or calcium carbonate

accept neutralisation or forms calcium sulfate

1

[10]

Q6.

(a) bar drawn correctly 78 – 80 (%)

1

(b) (i) (Mars has) no (green / living) plants / trees

1

(ii) (argon) is unreactive / inert

accept argon is a noble gas

ignore it is in Group 0

1

(c) (the amount of carbon dioxide has decreased because it has been) absorbed /

used by (green / living) plants / trees or used for photosynthesis

accept dissolved / absorbed by oceans or locked up in fossil fuels / carbonate rocks

1

(d) the eruption of volcanoes

1

[5]

Q7.

(a) (i) a reasonable attempt at a smooth curve

allow a curve which is close to but does not necessarily touch all points

1

(ii) any two from:

allow thicker / thinner / runny for viscous

• biodiesel is more viscous than petroleum diesel at all / lower

temperatures

• biodiesel – as the temperature increases the viscosity decreases or

vice versa

• petroleum diesel – the viscosity does not change

if no other mark awarded

allow 1 mark for any correct conclusion based on time or rate of flow

2

(iii) does not flow as easily (through pipes / engine)

allow could form a solid / block pipes / engine at low temperatures

or

needs a high temperature to flow

allow more difficult to vaporise / ignite

ignore burning

ignore references to viscosity

1

(b) (i) global dimming

allow correct description

1

(ii) 56 (%)

1

(iii) (increases) acid rain

1

because there is more nitrogen oxide(s)

ignore sulfur dioxide

if no other mark awarded

allow 1 mark for nitrogen oxide(s) given

1

(iv) answer yes or no does not gain credit because the marks are for

an explanation

ignore references to petroleum diesel

allow carbon for carbon dioxide

no

because carbon dioxide (26%) is released / produced

1

this will not all be absorbed by photosynthesis / growing plants for biodiesel

accept growing plants / farming uses machinery / fossil fuels releases carbon dioxide

OR

yes

because although carbon dioxide (26%) is released / produced (1)

this was absorbed by photosynthesis / growing plants (for biodiesel) (1)

allow this will be absorbed by photosynthesis / growing plants for biodiesel

1

[10]

Q8.

(a) crust

ignore Earth’s

1

core

ignore inner and/or outer

1

(b) bar chart

1

all heights are correct

accept correctly plotted points

1

all labels are correct for nitrogen, oxygen and other / argon

1

(c) (i) decomposed

1

(ii) global warming

1

[7]

Q9.

(a) (i) any two from:

• used by plants

allow specific plants and algae

• used for photosynthesis

ignore oxygen released / respiration

• absorbed / dissolved in oceans

ignore oceans formed

• locked up in fossil fuels / limestone / sedimentary rocks

2

(ii) calcium carbonate / CaCO3

1

decomposed / thermal decomposition

do not allow reaction with oxygen

accept quicklime / calcium oxide produced

CaCO3→ CaO + CO2 gains 2 marks

1

(b) increasing (CO2 or global warming)

1

more rapid increase recently

1

carbon dioxide causes global warming

accept greenhouse gas or

climate change / sea level rising

or ice caps melting

do not accept ozone layer or acid rain or global dimming

1

(c) (i) any one from:

• Wegener had no evidence / proof

accept movement too slow to measure

• other scientists had different ideas / views

accept continents / plates fixed or land bridge

• did not respect Wegener as a scientist / geologist

1

(ii) any three from:

• plates (move)

ignore continents

• heat energy / radioactivity (causes)

• convection currents

• in mantle

3

[11]

Q10.

(a) carbon / diesel / it reacts / burns in oxygen / air

1

limited supply (of oxygen / air)

accept incomplete combustion

2C + O2 → 2CO or

C + CO2 → 2CO gains 2 marks

1

(b) any four from:

accept converse statements for fossil diesel.

ignore cost / ease of manufacture / usage issues

for biodiesel:

• less global dimming (because fewer carbon particles)

• less acid rain (because less sulfur dioxide)

if neither point awarded, fewer carbon particles and less sulfur dioxide = 1 mark

• renewable resource / sustainable

accept fossil fuel / diesel supplies are limited

• use waste vegetable oils / fats

• vegetables / plants absorbed carbon dioxide / carbon neutral

accept fossil fuel / diesel releases locked up carbon / is not carbon neutral

• uses land which could be used to produce food

• third world countries can produce bio diesel

• biodegrades easily

• more NOx released

4

justified conclusion

1

[7]

Q11.

(a) (i) increase

1

(ii) energy is given out to the surroundings

1

(b) (i) NO

allow 2NO

ignore nitrogen oxide

do not allow equations

1

(ii) harmful / poisonous (owtte)

allow dangerous

ignore reference to pollution / global warming

do not accept references to ozone layer

1

(c) a catalyst can speed up a chemical reaction

1

different reactions need different catalysts

1

(d) (i) smaller

accept less / tiny / very small

allow 10-9

do not allow small unless qualified

1

(ii) reduce cost (owtte) or

ignore references to energy

save resources / raw materials (owtte)

1

[8]

Q12.

(a) gives out heat / energy

allow release / loses

allow the products have less energy

or

energy / heat transferred to the surroundings

ignore temperature rises

allow more energy given out in forming bonds than taken in to break bonds

1

(b) (i) speed up the reaction (owtte)

accept changes the rate

accept lowers activation energy

accept increases successful collisions

accept allows reaction to take place at a lower temperature

1

(ii) nitrogen (N2) / oxygen (O2) / products are safe or not harmful / pollutant /

toxic / dangerous / damaging

ignore releases nitrogen / oxygen unless qualified

or

(harmful) nitrogen monoxide / NO is not released into the air.

accept prevents / less acid rain

ignore greenhouse gas / ozone layer

1

(iii) 2 and 2

accept correct multiples or fractions

1

(iv) idea of catalyst not being used up

allow not changed by reaction

ignore catalyst does not take part

ignore catalyst not used in the reaction

1

(v) idea of different reactions (require different catalysts)

accept catalysts work for specific reactions

allow different gases

1

(c) • smaller / very small / or any indication of very small / 1–100 nanometres /

a few (hundred) atoms

ignore just small

ignore size of the converter

1

• big(ger) surface area

1

• less (catalyst) needed / small amount of catalyst needed

1

[9]

Q13.

(a) sulfur dioxide / SO2

allow sulfur oxide

1

(b) global dimming

1

(c) oxygen / O2

1

(d) (oil is a) limited resource / finite / non-renewable

accept running out of oil or wood is sustainable

accept (burning oil) increases amount of carbon dioxide in the atmosphere / global warming or releases locked up carbon / global dimming / acid rain

accept the oil (may become) too expensive

1

(e) carbon dioxide produced (from burning wood)

ignore global warming

1

carbon dioxide used by plants / trees or for photosynthesis

if no other mark awarded

allow carbon emissions used by plants / trees or for photosynthesis for 1 mark

1

[6]

Q14.

(a) complete diagram with 2 carbon atoms and 5 hydrogen atoms each C–C

and each C–H linked by a single line (bond)

1

(b) (i) the greater the number of (carbon) atoms (in an alkane molecule) the

greater its boiling point or vice versa

allow as the (carbon) chain gets longer the boiling point increases

ignore melting points

do not accept reference to greater number of molecules

1

(ii) they = hydrocarbons from the graph

it = C30H62

any two from:

• low boiling point / volatile

accept they are gases or liquids

• low viscosity

• high flammability

accept easier to burn / ignite

• small molecules

accept short chains

ignore number of carbon atoms

• burn completely

ignore speed of burning

2

(c) (i) 16 (CO2) + 18 (H2O)

1

(ii) (carbon dioxide in the Earth’s early) atmosphere

accept from volcanoes (millions of years ago)

or from dead plants / animals

allow dead sea creatures

ignore shells

1

(iii) increase in burning / use of fossil fuels

1

locked up carbon (carbon dioxide) is released

allow carbon / carbon dioxide from millions of years ago is released

accept extra carbon dioxide is not ‘absorbed’ (by the carbon cycle)

1

[8]

Q15.

any four from:

to gain 4 marks both pros and cons should be given

Arguments for biodiesel

max three from:

• sustainable / renewable

• (carbon neutral) absorbs CO2 when growing / during photosynthesis

• burning biodiesel produces low amounts particulates / carbon monoxide

allow burning biodiesel produces little / low amount of global dimming

ignore sulfur dioxide

• can use waste vegetable oils / fats (from food industry) or can use waste plant material

• can be used to conserve crude oil (instead of / mixed with petroleum diesel)

• produced by a low energy / temperature process

accept produced by a low tech process

• biodegrades (easily)

ignore engine effects

Arguments against biodiesel

max three from:

• creates food shortages

accept price of food increases

• deforestation to plant more crops leads to loss of habitat / biodiversity or deforestation leads to a reduction in absorption of CO2

allow burning trees increases CO2

allow deforestation increases global warming

• burning biodiesel produces high amounts of nitrogen oxides

allow increases acid rain

• crops takes time to grow

allow crops can fail

• vast areas of land needed to grow crops

4

conclusion supported by the argument presented, which must give added value to the points for and against given above

1

[5]

Q16.

(a) (thought to cause) global warming / green house (effect) / climate change

ignore other consequences of global warming

do not accept acid rain / ozone layer / global dimming

1

(b) any three from:

• replant trees / renewable / sustainable

ignore reusable

• carbon (dioxide) used by trees / photosynthesis

accept trees absorb carbon (dioxide) as they grow

ignore respiration

• it is a (continuous / carbon) cycle

accept burning wood is carbon neutral

or

carbon (dioxide) goes back into the air

for the second and third bullet points: accept trees use carbon dioxide which is released when (trees / wood are / is) burnt for 2 marks

• no new carbon (dioxide) is produced

or

no locked up carbon (dioxide) is released

or

the carbon (dioxide) was absorbed millions of years ago

3

[4]

Q17.

(a) acid rain → sulfur dioxide

1

global warming → carbon dioxide

1

global dimming → carbon particles

1

(b) (i) oxygen

1

(ii) carbon monoxide

1

(c) (i) decreasing

accept running out / none left

1

(ii) any two from:

it = coal

• world needs (more) energy

accept population is increasing

allow (greater) demand for coal / fuels / energy

• plentiful supply

accept readily available

allow coal will ‘last longer’

• (many) countries have coal

• easy to find / extract

• oil / gas is running out

accept need to use less oil / gas

accept need to use it to replace oil / gas

• cheap or cheaper than oil

2

[8]

Q18.

(a) (i) it = water vapour

condensed

accept temperature went below 100°C / boiling point of water

allow cooled to form liquid / water / rain

do not accept evaporated

1

formed the oceans / seas

ignore rain

accept (water vapour) cooled and formed the ocean / sea for 2 marks

1

(ii) any two from:

ignore oxygen / nitrogen increased

ignore reference to volcanoes / respiration

• used by (green) plants / algae

accept photosynthesis / plants give out oxygen

• changed into oxygen

• dissolved in oceans / seas

accept (locked up) in shells / skeletons (of animals)

• (locked up) in carbonates / sedimentary rocks

• (locked up) in fossil fuels / named fossil fuel

2

(b) (i) cannot get to / reach / drill to / see the core

accept the core is (too) far down (into the Earth) / do not know what happens under the crust / Earth’s surface

accept it is (too) hot / radioactive

ignore lack of evidence unqualified

1

(ii) any three from:

• heat / energy released

• from radioactive decay / processes

accept radioactivity / nuclear reactions

• (causing) convection currents

• in the mantle

3

[8]

Q19.

(a) (i) (thermal) decomposition

allow it breaks down

accept symbol equation or in words

allow reaction with SO2 (to form CO2)

1

(ii) calcium carbonate / calcium oxide / limestone / quicklime / it reacts with

sulfur dioxide / forms calcium sulfate

accept it neutralises sulfur dioxide / neutralisation

ignore references to sulfur

do not accept ‘calcium reacts with...’

1

(b) by incomplete / partial combustion (of the fuel)

1

insufficient oxygen / air (to burn fuel)

accept insufficient oxygen / air to burn fuel completely for 2 marks

if no other marks awarded

accept C + CO2 → 2CO or

2C + O2 → 2CO or in words for 1 mark

1

(c) (i) any two from:

• (CO2) from the atmosphere

• (CO2) taken in millions of years ago or early (atmosphere)

allow thousands / billions

allow rocks formed millions of years ago

• (CO2) was used to form the shells / skeletons of marine organisms /

fossil fuels

accept sedimentary rocks

allow used to form correct named fossil fuel

ignore limestone

2

(ii) any one from:

• (increases / enhances) global warming

allow greenhouse gas / effect

do not accept ozone layer / acid rain / global dimming

ignore consequences of global warming

• is additional carbon dioxide or not able to be absorbed by oceans /

seas or used by (green) plants

• acidification of sea water

1

[7]

Q20.

(a) (i) straight line through the ‘points’ and extended to C8H18

do not accept multiple lines

1

(ii) 5500

range 5400 to 5600

accept ecf from their graph

1

(iii) it is a straight line graph

allow directly proportional

accept constant difference between (energy) values

accept C5H12 close to values on the graph

or C5H12 comes in middle of the graph

ignore ‘fits the pattern’ unqualified

ignore ‘line of best fit’

ignore ‘positive correlation’

1

(iv) expected ranges for working are:

accept correct numerical answer as evidence of working

(5400 to 5600) – (2800 to 2900) = (2500 to 2800)

or

their value from (a)(ii) – a value from 2800 to 2900

or

(5400 to 5600) / their (a)(ii) divided by 2

or

a value from 2800 to 2900 - 2

1

no / not quite / almost / yes

this mark is only awarded on evidence from their correct working

1

(b) (i) incorrect / no or partially correct

ignore references to hydrogen

1

bio-ethanol produces least energy

mark independently

or

bio-ethanol produces 29 kJ

1

(ii) ignore incorrect / correct

any two from:

• hydrogen produces only H2O

accept hydrogen does not produce harmful gases / CO2 / SO2

• coal produces SO2

allow coal causes acid rain / respiratory problems

• coal produces smoke

allow coal causes global dimming

• both renewable and non-renewable fuels produce CO2

accept bio-ethanol and natural gas / coal produce CO2 / global warming

• (both) the non-renewable fuels produce CO2

accept coal and natural gas produce CO2 / global warming

• (both) renewable fuels produce no smoke

accept hydrogen and bio-ethanol do not produce smoke / global dimming

• (both) renewable fuels produce no SO2

accept hydrogen and bio-ethanol

do not produce SO2 / acid rain

2

[9]

Q21.

(a) (i) polyethene / poly(ethene)

accept polythene / polyethylene

1

(ii) needs heat / energy / high temperature / fuel (for cracking)

ignore other processes

1

produces carbon dioxide / CO2

ignore use of CO2 or ‘produces carbon’

1

(b) any three from:

• use water from local sources or water from close to home

• recycle bottles in the UK / close to home

accept do not recycle in other countries / Asia

• (reduction in distance travelled) would reduce CO2 emitted by transport

accept use of transport with low / no carbon dioxide emissions

• use tap water

• use glass bottles / waxed cartons / metal bottles

do not accept ‘do not use plastic bottles’ without an alternative material

• do not put in landfill or recycle more

• reuse / refill plastic bottles

• tax imported water / plastic bottles (to offset carbon cost)

• make more / all plastic bottles in UK

answers must be about the reduction of carbon cost

3

[6]

Q22.

(a) (i) nitrogen / N2

1

(ii) carbon dioxide / CO2

1

(b) (i) humans / scientists had not evolved

accept it was billions / millions of years ago

allow too long ago

1

(ii) temperature is above 100°C or any water would evaporate / boil

accept Venus is too hot

1

(c) any three from:

• used by plants

• used for photosynthesis

accept plants take in carbon dioxide and give out oxygen for the first two bullet points ie 2 marks

• dissolves in oceans / seas

allow absorbs into oceans / seas

• used to form the shells / skeletons of marine organisms

• locked up as limestone / carbonates

• locked up as fossil fuels / oil / coal

3

[7]

Q23.

(a) (i) (gases from) volcanoes

1

(ii) 100 allow 99

1

(iii) any two from:

• photosynthesis

• carbon dioxide used

allow carbon dioxide decreased

• oxygen produced

allow oxygen increased

ignore nitrogen / respiration

they = plants

2

(b) (i) any one from:

• sea floor spreading

accept oceanic ridges / magnetic stripes

• periodic measurements between continents

accept continents move a few centimetres each year

• evidence from rocks / fossils on different continents

accept continents fit together

• new mountain ranges

accept new islands

1

(ii) in the mantle

any two from:

• convection (currents) / movement

do not accept movement of the plates

• radioactivity / radioactive decay / nuclear reactions

1

• releases heat / thermal energy

accept heat from core

2

Q24.

(a) curve of best fit drawn through

or close to all of the points

1

(b) (i) 313

1

(ii) 1989 +/– 1

1

(c) concentration / amount of carbon dioxide has increased

1

recently the rate of increase is increasing

1

[5]

Q25.

(a) good (electrical) conductor

allow low reactivity / resistance to corrosion

do not accept heat conductor

1

(b) a mixture of metals

accept contains more than one type of metal

1

(c) (i) any one from:

• eyesore

• destruction of habitats

• pollution of water

• dust pollution

• noise

• traffic pollution

1

(ii) acid rain

allow sulfur dioxide is a pollutant

1

(d) (i) running out of copper (ores)

1

(ii) any two from:

• any specific example of using less copper

• reuse / recycle

allow do not throw copper / brass away

• use low-grade copper ores

• use other metals / materials in place of copper

2

[7]

Q26.

(a) (i) acid rain

accept consequences of acid rain

allow asthma / bronchitis

ignore toxic gas

1

(ii) global dimming

accept dimming alone

1

(b) (i) sustainable:

maximum two from:

• crops (that produce oil) can be grown in most places owtte

• renewable

• use less fossil fuels / diesel

• use (refined) waste oils

low pollution:

maximum two from:

ignore references to CO2 here

• most emissions are lower or any two named emissions from CO / SO2 / PM10 are lower

• much / lot less SO2 emissions (than the others) owtte

• accept spillages / waste is biodegradable

• less new CO2 or (more) carbon neutral

3

(ii) plants / photosynthesis use carbon (dioxide) from the air*

1

it / biodiesel releases carbon (dioxide) from plants / crops / photosynthesis*

(*) allow 1 mark for biodiesel is (more) carbon neutral

1

(fossil) diesel releases ‘locked up’ / new carbon (dioxide) / doesn’t

absorb CO2 / absorbed it millions of years ago

1

Q27.

(a) either:

calculations: all correct (ethanol = 6, methanol = 3,

peanut oil = 10, vegetable oil = 15)

ignore repetition of data from table unqualified

or

implication of correct calculation

(vegetable oil) gives largest temperature / heat increase per gram (owtte)

allow ‘produced most heat in proportion to the fuel used’ owtte for 1 mark

2

(b) any one from:

owtte

• smoke

ignore references to crops/food

• soot

• carbon

• carbon monoxide

• carbon dioxide

• global warming / climate change / greenhouse gases

• (air) pollution

• harmful/poisonous

1

scrub / wash the gases owtte

filter / remove (gases / fumes / appropriate named substance) owtte

(add extra oxygen) can burn more efficiently owtte

use a cleaner fuel owtte

plant more trees or similar linked to CO2

any sensible answer

‘don’t burn so much fuel’ insufficient alone

ignore extractor fans / air conditioning

1

(c) (i) A

1

(ii) B

1

[6]

Q28.

(a) (i) sulfur dioxide / SO2

1

(ii) global dimming

1

(iii) carbon dioxide / CO2

ignore ozone

1

increases the levels (of carbon dioxide)

accept it is a greenhouse gas or causes global warming / greenhouse effect

1

(b) gas / oil bar correct length

1

coal bar correct length

1

[6]

Q29.

(a) any two environmental problems with linked explanations

• global warming (1)

accept effects of global warming

caused by (formation of) carbon dioxide / greenhouse gas (1)

ignore greenhouse effect

• acid rain (1)

accept effects of acid rain

ignore respiratory problems

caused by ( formation of) sulfur dioxide (1)

accept sulfur oxide

ignore sulfuric acid

• global dimming (1)

ignore respiratory problems

caused by ( formation of) particles / particulates / fires /

smoke / carbon / pm 10 (1)

• scarring of landscape (1)

caused by mining / quarrying of coal (1)

ignore ozone layer

max 4

(b) any three from:

• replant the trees / renewable / sustainable

ignore reusable

• carbon dioxide is used by the trees / photosynthesis

accept trees absorb carbon dioxide as they grow

do not allow respiration

• it’s a (continuous carbon) cycle

accept ‘carbon dioxide goes back into the air’

accept trees use CO2 which is released when trees are burnt

• no ‘new’ carbon (dioxide) is produced or

no locked up carbon (dioxide) is released

accept no carbon (dioxide) from fossil fuels is produced

3

[7]

Q30.

(a) any two from:

asks for cause therefore no marks for just describing the change

must link reason to a correct change in a gas

carbon dioxide has decreased due to:

accept idea of ‘used’ to indicate a decrease

• plants / micro organisms / bacteria / vegetation / trees

• photosynthesis

ignore respiration

• ‘locked up’ in (sedimentary) rocks / carbonates / fossil fuels

• dissolved in oceans

ignore volcanoes

oxygen has increased due to:

accept idea of ‘given out / produced’

• plants / bacteria / micro organisms / vegetation / trees

• photosynthesis

ignore respiration

nitrogen increased due to:

accept idea of ‘given out / produced’

• ammonia reacted with oxygen

• bacteria / micro organisms

ignore (increase in) use of fossil fuels / deforestation

2

(b) (because methane’s) boiling point is greater than the average /

surface temperature or Titan’s (average / surface) temperature

is below methane’s boiling point

ignore references to nitrogen or water

1

any methane that evaporates will condense

accept boils for evaporates

accept cooling and produce rain for condensing

1

(c) (i)

bonds must be displayed correctly

ignore bond angles

1

(ii) poly(propene) / polypropene / polypropylene

do not allow polypropane

any two from:

• double bonds open up / break / become single(*)

• propene molecules / monomers / they join / undergo addition

polymerisation(*)

1

• form chains / long molecules(*)

(*)correct chemical equation gains 2 marks

ignore large

using monomer incorrectly max 2 marks

2

Q31.

(a) oxygen and nitrogen

1

20 – 21 % and 78 – 80 %

accept any two correct responses in the correct space for one mark

1

(b) (i) acid rain

accept toxic gas or consequence of acid rain

1

(ii) idea of the removal or use of sulfur

dioxide gas (from the waste gases)

do not accept remove sulfur from coal

1

(iii) oxygen

accept O2

1

water

accept H2O

accept hydrogen oxide / steam

1

(c) any two from:

• it’s a ‘greenhouse gas’ or increase greenhouse effect

accept action of a ‘greenhouse gas’

• causes global warming or increase in the Earth’s temperature

• sea-levels rise or flooding

• climate change

• (polar) ice-caps melt

• extension of deserts

mention of ozone / acid rain / global dimming = max 1 mark

2

(d) idea trap / store / lock the carbon dioxide

1

in the oil reservoir or under the sea bed

do not accept ‘into the oil’ / ‘under the sea’

1

[10]

Q32.

(a) hydrogen

ignore formulae

1

(b) any two from:

• different sized molecules / more or less (carbon) atoms (in molecules)

ignore different densities

• fuels have different boiling points

• fuels condense at different temperatures

2

(c)

all three correct = 3 marks

two correct = 2 marks

one correct = 1 mark

3

[6]

Q33.

(a) core

ignore outer or inner

1

mantle

1

(b) (i) carbon dioxide

accept formula CO2

1

oxygen

accept formulae O2 / O

1

(ii) 4%

1

(iii) carbon dioxide has decreased / from 95% to 0%

1

oxygen has increased / from 0% to 21%

1

any one from:

(carbon dioxide decrease)

• carbon dioxide used during photosynthesis / by plants

• carbon dioxide dissolves in oceans

• carbon dioxide is locked up in rocks / carbonates / fossil fuels

(oxygen increase)

• oxygen released during photosynthesis / by plants

1

Q34.

(a) (i) Cu2S + 2O2 2CuO + SO2

accept fractions and multiple

1

(ii) any two from:

• sulfur dioxide

accept sulphur dioxide / sulphur oxide / SO2

• causes acid rain

ignore other comments eg global warming / ozone / global dimming / greenhouse effect

• consequence of acid rain eg kills fish / plants

2

(b) any two from:

• heat (copper oxide with carbon)

• oxygen is removed by carbon

accept copper (oxide) loses oxygen

or

carbon gains oxygen

accept carbon oxide

or

carbon monoxide / carbon dioxide is produced

or

carbon displaces copper

accept a correct word or balanced

symbol equation

• because carbon is more reactive than copper

allow a correct comparison of reactivity

2

(c) (i) electrolysis

accept electroplating

1

(ii) (electrical) wiring / appliances / coins / pipes / cladding for

buildings / jewellery / making alloys

1

or

named alloys

(d) any three explanations from:

for recycling

• less acid rain (pollution)

• copper reserves last longer / conserved

or

do not run out

• energy for extraction (saved)

or

less energy required

• less mining / quarrying

• less waste (copper) / electrical appliances dumped

or

less landfill

against recycling

• collection problems

• transport problems

• difficult to separate copper from appliances

• energy used to melt the collected copper

ignore electrolysis / pollution

ignore ideas about less machinery / plant

ignore idea of cost

3

[10]

Q35.

(a) (i) core

1

(ii) plate (boundaries)

accept parts of the crust

ignore crust alone

1

sudden movement / colliding

accept movement but ignore movement apart

or

normally move a few centimetres per year

accept continental drift

1

convection currents / driven by heat from radioactive processes / decay

idea of source of energy for the movement

1

the idea of uncertainty with an explanation

eg scientists do not know (with any certainty)

• what happens under the crust

• where the forces / pressure are building up

• we cannot measure the forces

• when the forces reach their limit

ignore references to volcanoes

1

(b) (i) 78

(ii) marks awarded for any 2 gases from the following 3 gases

max 3 marks from CO2

1

any four from:

ignore references to respiration

carbon dioxide has decreased:

• used by plants / bacteria (stromatolites)

• during photosynthesis (must be linked to CO2 decrease)

• ‘locked up’ in (sedimentary) rocks / carbonates / fossil fuels

• dissolved in oceans

and / or

oxygen has increased because:

• released by plants / bacteria (stromatolites)

• during photosynthesis (must be linked to O2 increase)

and / or

nitrogen has increased because

• ammonia reacted with oxygen (to release nitrogen)

• nitrogen is released by bacteria

4

[10]

Q36.

(a) any three from:

accept reverse answers if unambiguous

do not accept just different throughout

3

less / little / not much carbon dioxide or give a %age < 1%

more / a lot of nitrogen or give 78-80%

(more) / (some) oxygen or give a %age 20-21%

do not accept more “other gases”

references to pollutant gases in general or named examples

e.g. CO, SO2, NO, NOX etc.

more / some water (vapour)

some / 1% argon

ignore other noble gases

ozone (layer) on earth

(b) any two from:

removed carbon dioxide

ignore reference to respiration /

photosynthesis unless qualified

released oxygen

caused carbon from carbon dioxide to

become locked in sedimentary rocks

the oxygen they produced reacted with

methane and ammonia

produced nitrogen (must be linked to fourth point)

accept correct word / symbol equation for photosynthesis for 2 marks

converted / changed CO2 to oxygen for 2 marks

2

[5]

Q37.

(a) (i) water vapour given out from volcano

accept steam

not hydrogen and oxygen combining

to form water

1

condensed

accept rain / clouds formed just ‘cools’ is insufficient

1

(b) nitrogen (left) N

do not accept N

1

oxygen (right) O

do not accept O

1

[4]

Q38.

Quality of written communication:

for correct sequencing or linking of two ideas or two points

annotate Q or Q

1

any three from:

ignore superfluous statements

• B is least energy efficient in terms

of cost (kJ per p), so A = C = D in

terms of cost or B is the most

expensive in terms of energy

efficiency

owtte

accept B is poor value for money / B is most expensive

one is insufficient for mark

• D is 1st, since gives only water as product or gives no harmful

products / gases or there are no pollutants

owtte

• A is 2nd best, since produces CO2 owtte

• C is 3rd, since gives SO2 owtte

if no other marks, then D A C B – based on energy per kJ

per 100g only = 1 mark and Q mark if 2 ideas are linked

3

[4]

Q39.

(a) Quality of written communication

for any two ideas sensibly stated

1

any three from:

• plants take in (CO2)

accept photosynthesis uses (CO )

• converted to glucose / starch / carbohydrates

ignore carbon compounds by itself

• CO2 locked up in fossil fuels

accept coal / oil / natural gas / methane for fossil fuels

• CO2 reacts with / dissolves (sea)water

accept ocean removes CO2

• producing hydrogencarbonates

accept carbonic acid

• producing carbonates

accept named carbonates

• marine animals use carbonates to make shells

do not accept bones

• forms sedimentary rocks

accept limestone / chalk

accept marble

do not accept sediments alone

3

(b) any two from:

• burning of fossil fuels or cars /

industry / air travel / power stations

ignore increase in population

ignore more use of electricity

• natural processes cannot absorb all the extra CO2

• deforestation

accept less photosynthesis

ignore volcanic activity

accept burn trees

2

[6]

Q40.

(a) hydrocarbon is a compound

not mixture not substance

1

containing carbon and hydrogen

accept of the elements carbon and hydrogen

accept of carbon and hydrogen

contains hydrogen and carbon only (2)

1

(b) (i) any order

carbon dioxide

accept CO2

exact formulae

2

water 1

accept H2O

not carbon in one box and dioxide in second box (0)

ignore any attempt to ‘balance’ the equation

(ii) it is poisonous

accept toxic

can kill you

accept any reasonable description

of its effect on red blood cells or on

haemoglobin in terms of reducing

oxygen transport

not can explode, harmful,

dangerous, flammable

1

[5]

Q41.

(a) respiration

combustion

1 mark each

2

(b) methane

water

1 mark each

accept steam

do not accept natural gas for methane

do not accept hydrogen oxide

2

(c) greenhouse effect (increased)

accept (global) warming

accept polar ice caps melt

accept rising sea levels

accept problems with climatic change

do not accept changes to the weather or acid rain

1

[5]

Q42.

(a) N2

1

20–21%

accept an answer in this range

1

Ar

1

(b) (i) compound of carbon and hydrogen only

do not accept ‘mixture’

1

(ii) Oxygen or O2

1

(iii) exothermic

accept combustion or oxidation

1

(iv) increases greenhouse effect

1

global warming or example

1

[8]

Q43.

(a) organic

1

sediment

1

(b) (i) gases

1

(ii) bitumen

1

(c) (i) cracking

accept thermal decomposition

do not accept endothermic

1

(ii) many or short or small (ethene) molecules

accept monomer

accept double bonds open up or break

1

join to make larger molecules

accept polymer

accept polymerisation

accept short chain to long chain (or molecules)

do not accept unsaturated to saturated

1

(d) poor ventilation

accept limited air supply

accept insufficient oxygen

1

causes incomplete combustion

accept produces CO

1

(fumes contain) carbon monoxide which dangerous

toxic is not awarded a mark

do not accept harmful or poisonous

1

[10]

Q44.

(a) 95% (1 mark for working)

2

(b) Much less carbon dioxide

Much more nitrogen

2

(c) Plants take up CO2

plants give out oxygen

when they die trap CO2 in rocks and fossil fuels

methane and ammonia reacted with oxygen

nitrogen gas produced

by reaction of oxygen and ammonia

and by denitryfying bacteria

formation of ozone layer

any 4 for 1 mark each

4

[8]

Q45.

nitrogen – Gas A (or N2) (N) = 1)

oxygen – Gas B (or O2) (O)

for 1 mark each

[2]

Q46.

(a) amount of CO2 (much) lower

amount of O2 (much) higher

amount of N2 (much) higher (owtte.)

less other gases/less NH3/less CH4

any 2 for 2 marks

2

(b) 4 points from:

plants (evolved)/photosynthesis/algae

take in CO2

give out O2

water vapour condensed

ozone formed from oxygen

less CO2 is produced now from volcanic activity

CO2 from air trapped in sedimentary rocks or fossil fuels

nitrogen produced by bacteria/living organisms/microbes/decay of dead

organisms (not nitrifying bacteria, nitrogen fixing 4 bacteria)

nitrogen produced by reaction of NH3 with O2/decomposition of NH3

nitrogen builds up because it is unreactive

(Assume answer refers to today’s atmosphere)

any 4 for 1 mark each

4

[6]

Q47.

(a) combustion

for one mark

1

(b) B

for one mark

1

[2]

Q48.

(a) (i) burning / breathing / respiration / fuels / food

for 1 mark each

2

(ii) 1. rock is heated / subducted (owtte) / close to magma / melted

1. rock is decomposed / carbon dioxide released through volcanoes

for 1 mark each

2

(b) carbon dioxide reacts / dissolves in sea-water / dissolves in rain water

insoluble carbonates / calcium carbonate are / is formed carbon dioxide turned into shells / coral / limestone / chalk / sediments also soluble hydrogencarbonates (calcium / magnesium) are formed photosynthesis by plants

any three for 1 mark each

3

(c) (i) sea unable to absorb all the extra carbon dioxide being produced

more trees being cut down / deforestation increased burning of fuels / more cars / more industry (not more people)

any one for 1 mark

1

(ii) global warming / greenhouse effect or effects such as melting ice caps /

rising sea levels / climatic change / more deserts

(not changes to ozone layer)

for one mark

1

[9]

Q49.

(a) any two 1 mark each

burning / combustion

fossil fuels or (locked up) carbon

accept fuel / named fuel

oxygen used

2

(b) any three from

produces (calcium) carbonate

which is insoluble

produces (calcium) hydrogencarbonate

which is soluble

photosynthesis

releases oxygen

3

[5]

Q50.

(a) (i) nitrogen (gas) or N2

if only the formula is given it must be correct in every detail

1

(ii) argon (gas) or Ar

1

(iii) oxygen (gas) or O2

1

(b) vapour

1

evaporating

1

sea(s)

1

condenses

1

(c) volcanoes or volcanic activity or the sea(s)

allow carbonates(s) (rocks)

do not credit inside

1

[8]

Q51.

(a) (i) fractional distillation

both words required

accept fractionation

1

(ii) any one from

ethane

propane

butane

1

(b) (i) carbon dioxide

1

water (vapour)

accept steam

do not credit symbols

1

(ii) carbon monoxide

accept CO

do not credit soot or carbon oxide

1

[5]

Q52.

(a) either any two points (1) each from

* (surface) below 100 °C (the surface) below the boiling point

of water

* (allowed the) condensation (of water vapour)

accept (rate of) condensation greater than (the rate of) evaporation

* from the atmosphere

accept from the air

or condensed water (vapour) (1)

was pulled by gravity into depressions (1)

or idea of impervious sea bed

or from comets (which crashed on the Earth) (1)

ice (from these) melted (1)

2

(b) any two processes (1) each from

* dissolving in (sea) water

* (taken in during) photosynthesis

accept taken in by algae or plants

• formation of carbonate(s)

or calcium carbonate or chalk or

calcite

accept formation of shells or bones or corals

2

[4]

Q53.

(a) nitrogen and oxygen

both required either order

1

(b) (i) any two from

(atmosphere) is now cooler water vapour has condensed

to form sea(s) / ocean(s)

2

(ii) any two from

has dissolved in / reacted with seawater has formed carbonates

(evolution of green) plants removed by photosynthesis

has formed fossil fuels

2

(c) (i) 225

accept any date in the Triassic period

225 – 191 (mya)

do not credit 190 (mya)

1

(ii) on different (tectonic) plates

or answer refers to African and South American plates

1

(movement) due to convection currents in the mantle

1

due to energy / heat from the core

or due to radioactivity

1

[9]

Q54.

(a) substances/chemicals/compounds

gains 1 mark

but gases (accept vapours)

gains 2 marks

heat (accept light)

for 1 mark

3

(b) carbon dioxide/CO2

water (vapour)/H2O

sulphur dioxide/SO2

(accept correct formulae)

in any order for 1 mark each

3

[6]

Q55.

(a) (i) oxygen (not air)

(ii) oxides/monoxides/dioxides

for 1 mark each

Do not allow specific examples

2

(b) (i) water

(ii) sulphur

(iii) carbon

for 1 mark each

3

(c) gives out/releases heat/energy

for 1 mark

1

(d) (i) carbon dioxide

(ii) carbon

for 1 mark each

(allow correct symbols/formulae)

2

[8]

Q56.

(a) each bar correct height (2 bars) to less than ½ square

1 mark for each

both bars correctly labelled (in relation to size of bars)

for 1 mark

3

(b) less

gains 1 mark

but a lot less / much less / 18 times less or more if referring to coal

gains 2 marks

2

(c) (i) carbon

sulphur

for 1 mark each

2

(ii) ideas that

• at high temperatures, (produced when fuels burn)

• nitrogen and oxygen from atmosphere combine / react

for 1 mark each

2

[9]

Q57.

(a) both bars correct height (to better than half a square)

1 mark for both

both bars correctly labelled

(w.r.t. relative heights if these incorrect)

for 1 mark

2

(b) a lot less / much less / 18 times less (converse must specify coal)

gains 1 mark

1

(c) ideas that

• at high temperatures (produced when fuels burn)

• nitrogen and oxygen from air / atmosphere combine / react

or nitrogen from air / atmosphere oxidises

for 1 mark each

2

(d) ideas that

• coal produces most carbon dioxide / more CO2 than gas / oil

• because coal is (mostly) carbon

• gas produces less carbon dioxide than coal / oil

• oil and gas also contain hydrogen / contain more hydrogen atoms than carbon atoms / also produce water

any three for 1 mark each

3

(e) sulphur

for 1 mark

2

[9]