Q1. In the carbon cycle the amounts of carbon dioxide and oxygen in the air are changed by several processes. (a) The names of some processes are given in the box below. Choose the correct process for each box in the diagram. The first one has been done for you. (2) combustion decomposition neutralisation photosynthesis respiration (b) Fossil fuels, such as natural gas, react with oxygen. CH 4 + 2O 2 → CO 2 + 2H 2 O .......................... + oxygen → carbon dioxide + .......................... Complete the word equation for this reaction (2) (c) What problem is caused by the formation of large amounts of carbon dioxide? ..................................................................................................................................... ..................................................................................................................................... (1) (Total 5 marks) Page 1 of 33
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Q1. In the carbon cycle the amounts of carbon dioxide and oxygen in the air are changed by several processes.
(a) The names of some processes are given in the box below.
Choose the correct process for each box in the diagram. The first one has been done for you.
(2)
combustion decomposition neutralisation
photosynthesis respiration
(b) Fossil fuels, such as natural gas, react with oxygen.
Q2. (a) During the first billion years of the Earth’s existence, there were many active volcanoes. The volcanoes released the gases that formed the early atmosphere.
Describe how volcanoes caused the oceans to be formed.
(b) The atmosphere on Earth today is very different from the early atmosphere.
The pie chart shows the amounts of different gases in the air today. Choose gases from the box to label the pie chart.
(2)
(Total 4 marks)
argon carbon dioxide hydrogen nitrogen oxygen
Page 2 of 33
Q3. Global warming is thought to be happening because of the increased burning of fossil fuels. The concentration of carbon dioxide in the air from 1905 to 2005 has been calculated.
(a) Draw a line of best fit for these points. (1)
(b) (i) What was the concentration of carbon dioxide in 1955?
Q4. The bar chart below shows the percentage by mass of gases in dry air. Two of the gases are labelled as A and B.
What are the names of gas A and gas B?
Gas A is ................................................................................................................................
Gas B is ................................................................................................................................ (Total 2 marks)
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Q5. Life on Earth would not exist without the atmosphere. Billions of years ago the composition of the Earth’s atmosphere was very different from the composition today.
(a) Label the pie chart below to show the percentages and names of the two main gases in the Earth’s atmosphere today.
(2)
(b) There is evidence that the composition of the Earth’s atmosphere is still changing. One possible reason is that many power stations generate electricity by burning fossil fuels such as coal, oil or natural gas. Sulfur dioxide, SO
2, is produced when coal burns in air.
(i) What environmental problem does sulfur dioxide cause?
(d) Carbon dioxide is produced when fossil fuels burn in power stations. The diagram represents one idea to prevent excess carbon dioxide from entering the atmosphere.
Use the diagram to explain how carbon dioxide can be prevented from entering the atmosphere.
Average surface temperature –23 °C Average surface temperature 15 °C
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(b) Titan is the largest moon of the planet Saturn. It has an atmosphere that, like the Earth’s, contains mainly nitrogen. Methane is the other main gas.
When it rains on Titan, it rains methane! Explain why.
Q14. For 200 million years the proportions of the different gases in the atmosphere have been much the same as today. Over the past 150 years the amount of carbon dioxide in the atmosphere has increased from 0.03% to 0.04%.
(a) Describe how carbon dioxide is released into the atmosphere:
Q15. The amount of carbon dioxide in the atmosphere is increased by reactions that occur in internal combustion engines (X) and is decreased by reactions in sea water (Y).
Describe, in as much detail as you can, the reactions which take place at X and Y.
(a) X .................................................................................................................................
Q16. (a) Apart from water vapour, two gases account for about 99% of the present atmosphere of our planet.
What are the names of these gases?
.......................................................... and ........................................................ (1)
(b) Scientists now have evidence that, over three billion years ago, our planet’s atmosphere was mostly a mixture of water vapour, carbon dioxide, methane and ammonia. Since then the mixture has gradually changed.
(i) Suggest why there is now less water vapour in the atmosphere.
(c) The following information suggests that the continents of Africa and South America were once joined together but then began to move apart.
Fossilised remains of a large fern-like plant called Glossopteris have been found in the rocks of the Carboniferous period in both Africa and South America.
Fossilised remains of a freshwater reptile called Mesosaurus have been found in the rocks of the Permian period in both Africa and South America.
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No fossils of identical organisms have been found in the rocks of the Jurassic or the Cretaceous period in Africa or South America.
The following table gives the names of some of the periods in our planet’s geological history.
Start of the period millions of years ago
Name of the period
2 Quaternary
65 Tertiary
136 Cretaceous
190 Jurassic
225 Triassic
280 Permian
345 Carboniferous
395 Devonian
435 Silurian
500 Ordovician
570 Cambrian
(i) Use this information to suggest when Africa and South America began to move apart.
About ......................................................... million years ago. (1)
(ii) What conditions were necessary for Africa and South America to move apart?
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
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(ii) poly(propene) / polypropene / polypropylene do not allow polypropane
• 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
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(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]
M13. (a) amount of CO2 (much) lower
amount of O2 (much) higher
amount of N2 (much) higher (owtte.)
less other gases/less NH3/less CH
4
any 2 for 2 marks 2
(b) 4 points from: plants (evolved)/photosynthesis/algae take in CO
2
give out O2
water vapour condensed ozone formed from oxygen less CO
2 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 NH
3 with O
2/decomposition of NH
3
nitrogen builds up because it is unreactive (Assume answer refers to today’s atmosphere)
(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
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(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]
M15. (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]
M16. (a) nitrogen and oxygen
both required either order 1
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(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