Quickfire: the gases in today's atmosphere. Choose the correct answer for each question.
(a)Which gas makes up approximately 78% of the Earth's atmosphere today?(1)
A) Oxygen
B) Nitrogen
C) Carbon dioxide
D) Argon
(b)Which gas makes up approximately 21% of the Earth's atmosphere today?(1)
A) Nitrogen
B) Argon
C) Oxygen
D) Carbon dioxide
(c)Approximately what percentage of today's atmosphere is carbon dioxide?(1)
A) 21%
B) 4%
C) 0.04%
D) 78%
(d)Which noble gas makes up just under 1% of today's atmosphere?(1)
A) Helium
B) Neon
C) Argon
D) Krypton
2
The table shows the approximate composition of today's atmosphere (dry air). Complete the table.
(a)State the approximate percentage of nitrogen in today's atmosphere.(1)
(b)State the approximate percentage of argon in today's atmosphere.(1)
(c)State the approximate percentage of carbon dioxide in today's atmosphere.(1)
(d)Name one other gas present in today's atmosphere in trace amounts (other than argon or carbon dioxide).(1)
3
Required practical: measuring the percentage of oxygen in air. Aaliyah investigates the percentage of oxygen in air using excess copper heated strongly in a horizontal glass tube connected to two gas syringes. Air is passed back and forth over the heated copper until the volume of gas in the syringes stops changing.
(a)Name the piece of apparatus used to measure the volume of gas in this practical.(1)
(b)State the gas that makes up most of the volume of gas remaining in the syringes at the end of the experiment.(1)
(c)Complete the word equation for the reaction that occurs: copper + oxygen -> ______(1)
(d)Explain why the copper is heated strongly and why the air is passed back and forth between the syringes several times.(2)
(e)Aaliyah recorded a starting volume of 100 cm3 of air. Once the tube had cooled fully to room temperature, the final volume of gas remaining was 79 cm3. Calculate the percentage of oxygen in the air sample. Show your working.(3)
(f)Explain, in terms of the gases present, why the volume of gas stops decreasing even though unreacted copper remains in the tube.(2)
(g)Aaliyah read the final volume before the apparatus had fully cooled to room temperature. Explain the effect this would have on the calculated percentage of oxygen.(2)
(h)Suggest one improvement to the method that would make the calculated percentage of oxygen more accurate.(2)
4
The Earth's atmosphere has changed enormously since the Earth formed about 4.6 billion years ago.
(a)State two gases thought to have made up most of the Earth's early atmosphere.(2)
(b)Name the process, linked to activity inside the Earth, that released these gases to form the early atmosphere.(1)
(c)Explain how the oceans are thought to have formed from this early atmosphere.(1)
5
About 2.7 billion years ago, simple photosynthesising organisms called cyanobacteria (blue-green algae) evolved in the early oceans.
(a)Write a word equation for photosynthesis.(1)
(b)Explain how the evolution of these organisms led to a large increase in the percentage of oxygen in the atmosphere over hundreds of millions of years.(2)
(c)Suggest why it took hundreds of millions of years for oxygen to build up in the atmosphere, rather than happening quickly.(1)
6
The greenhouse effect is essential for life on Earth. Define what is meant by the term 'greenhouse effect'.
(3)
7
Human activity has increased the concentration of certain gases in the atmosphere since the industrial revolution, enhancing the natural greenhouse effect.
(a)Name two greenhouse gases whose atmospheric concentration has increased mainly due to human activity since the industrial revolution.(2)
(b)Explain how increasing the concentration of these gases in the atmosphere leads to global warming (the enhanced greenhouse effect).(2)
8
The table shows measured atmospheric carbon dioxide concentration at three points in time. Year: 1960, CO2 concentration: 315 ppm Year: 1990, CO2 concentration: 355 ppm Year: 2020, CO2 concentration: 415 ppm
(a)Calculate the increase in atmospheric CO2 concentration between 1960 and 2020.(1)
(b)Calculate the mean rate of increase in CO2 concentration, in ppm per year, between 1960 and 2020. Give your answer to 2 decimal places.(2)
(c)Calculate the percentage increase in CO2 concentration from 1960 to 2020. Give your answer to 1 decimal place.(2)
9
Data (see Q8) shows that as atmospheric carbon dioxide concentration has increased since 1960, global average temperature has also increased. A student claims this proves that rising carbon dioxide caused all of the observed temperature rise. Evaluate this claim.
(3)
10
The table shows estimated carbon dioxide equivalent (CO2e) emissions for a family holiday. Activity: Return flight Manchester to Tenerife, CO2e emitted: 620 kg Activity: Car journey, 100 miles round trip (petrol car), CO2e emitted: 32 kg
(a)The Obi family takes the flight and the car journey shown in the table. Calculate their total carbon footprint, in kg CO2e, for these two activities.(1)
(b)The Campbell family takes the same flight but travels to and from the airport by train instead of by car, producing only 6 kg CO2e for the journey. Calculate how much lower the Campbell family's total carbon footprint is compared with the Obi family's, from part (a).(2)
(c)A magazine article claims that 'a short-haul return flight produces about 4 times more CO2e than the equivalent car journey'. Use the data in the table to determine whether this claim is supported.(2)
11
Match each human activity to the greenhouse gas it mainly increases in the atmosphere.
(a)Burning fossil fuels in power stations and vehicles mainly increases the concentration of which greenhouse gas?(1)
(b)Cattle farming and rice paddy fields mainly increase the concentration of which greenhouse gas?(1)
(c)Explain how large-scale deforestation increases the concentration of carbon dioxide in the atmosphere through two separate effects.(1)
(d)Landfill sites, where household rubbish decomposes without oxygen, mainly release which greenhouse gas?(1)
12
Climate change is expected to have a range of effects on the environment and on human life.
(a)Explain why global warming is expected to cause sea levels to rise.(2)
(b)State two other possible effects of climate change on the environment or human life, other than sea level rise.(2)
13
Burning fuels can release pollutants into the atmosphere in addition to carbon dioxide.
(a)Name the pollutant gas produced when fuels containing sulfur impurities are burned, which is a cause of acid rain.(1)
(b)Name the poisonous gas produced by incomplete combustion of fuels, which reduces the ability of red blood cells to carry oxygen.(1)
(c)Name the solid particles released by incomplete combustion, which can contribute to global dimming and respiratory problems.(1)
(d)Name the gases formed when nitrogen and oxygen from the air react together inside a car engine at high temperature, which also contribute to acid rain.(1)
(e)Explain the effect that particulates released into the atmosphere have on the amount of sunlight reaching the Earth's surface.(1)
14
Natural gas boilers burn methane completely in oxygen from the air: methane + oxygen -> carbon dioxide + water. 16 g of methane reacts completely with 64 g of oxygen to produce 44 g of carbon dioxide and 36 g of water.
(a)Show that these masses are consistent with the law of conservation of mass.(1)
(b)A boiler burns 8 g of methane completely. Calculate the mass of carbon dioxide produced.(2)
(c)Calculate the mass of oxygen needed to completely burn 8 g of methane.(1)
15
24 g of magnesium ribbon is burned completely in oxygen from the air. The magnesium oxide produced has a mass of 40 g.
(a)Calculate the mass of oxygen from the air that reacted with the magnesium.(2)
(b)Explain, in terms of the atmosphere, where this oxygen came from.(1)
16
Evaluate the evidence that human activities are the main cause of the recent rapid increase in global average temperature, and discuss what could be done to reduce future increases in atmospheric carbon dioxide concentration.
(6)
17
Carbon moves between the atmosphere, living things, and the Earth through the carbon cycle.
(a)Name the process by which green plants and algae remove carbon dioxide from the atmosphere.(1)
(b)Name the process, carried out by all living organisms, that releases carbon dioxide back into the atmosphere.(1)
(c)Name the process by which the remains of dead plants and animals, under high pressure and temperature over millions of years, can form carbon-containing fuels such as coal, oil and natural gas.(1)
(d)Explain why burning fossil fuels releases carbon dioxide into the atmosphere much more rapidly than it was originally removed by living organisms.(1)
18
Individuals and households can take action to reduce their carbon footprint.
(4)
19
Scientists drill deep into ice sheets in Antarctica and Greenland to remove long cylinders of ice called ice cores. Explain how scientists can use ice cores to estimate both the atmospheric carbon dioxide concentration and the temperature of the atmosphere from thousands of years ago.
(3)
20
Quickfire true or false: for each statement about the Earth's atmosphere, state whether it is True or False.
(a)"Today's atmosphere contains a much higher percentage of oxygen than the Earth's very early atmosphere."(1)
True
False
(b)"Carbon dioxide makes up about 21% of today's atmosphere."(1)
True
False
(c)"The greenhouse effect is a natural process that keeps the Earth warm enough to support life."(1)
True
False
(d)"Burning fossil fuels releases carbon that has been stored underground for millions of years back into the atmosphere as carbon dioxide."(1)
True
False
(e)"Nitrogen is classed as a significant greenhouse gas because it strongly absorbs infrared radiation."(1)
True
False
Mark scheme · K10 The Earth and its Atmosphere
Question 1
(a) B1 B - nitrogen
(a) Answer: B (nitrogen)
(b) B1 C - oxygen
(b) Answer: C (oxygen)
(c) B1 C - 0.04%
(c) Answer: C (0.04%)
(d) B1 C - argon
(d) Answer: C (argon)
Question 2
(a) B1 78% (accept 77-79%)
(a) Answer: 78%
(b) B1 0.9% (accept 0.8-1%)
(b) Answer: 0.9%
(c) B1 0.04% (accept 0.03-0.05%)
(c) Answer: 0.04%
(d) B1 any one from: neon, helium, methane, water vapour, hydrogen, krypton (oe)
(d) Answer: e.g. water vapour
Question 3
(a) B1 gas syringe
(a) Answer: Gas syringe
(b) B1 nitrogen
(b) Answer: Nitrogen
(c) B1 copper oxide
(c) Answer: Copper oxide
(d) M1 heating strongly provides the energy needed for the copper to react with oxygen at a reasonable rate (oe)
(d) M1 passing the air back and forth ensures all of the air (and all of the oxygen within it) comes into contact with the hot copper, so the reaction goes to completion (oe)
(d) Answer: Strong heating lets the copper react readily with oxygen; passing the air back and forth repeatedly ensures every part of the air sample contacts the copper so all the oxygen is removed.
(e) M1 decrease in volume = 100 - 79 = 21 cm3
(e) M1 percentage = (21 / 100) x 100
(e) A1 21% cao
(e) Answer: 21%
(f) B1 all of the oxygen originally present in the air has now reacted with the copper
(f) B1 the remaining gas is mostly (unreactive) nitrogen, which does not react with copper (oe)
(f) Answer: All the oxygen has already reacted; the leftover gas is mainly nitrogen, which will not react with the copper even though copper remains.
(g) M1 a warm gas has a larger volume than the same gas at room temperature (gas expands on heating), so the final volume reading would be higher than it should be
(g) M1 this gives a smaller calculated decrease in volume, so the calculated percentage of oxygen would be an underestimate (too low) ft from reasoning
(g) Answer: The percentage of oxygen calculated would be too low (an underestimate).
(h) B1 a valid improvement, e.g. allow the apparatus to cool fully to room temperature before taking the final reading; check the apparatus is gas-tight with no leaks; use a larger starting volume of air and repeat/average results
(h) B1 a linked explanation of why this improves accuracy (oe)
(h) Answer: e.g. Allow the tube to cool completely to room temperature before reading the final volume, because this removes the effect of gas expansion on the reading.
Question 4
(a) B1 carbon dioxide
(a) B1 water vapour (accept nitrogen as an alternative to either mark)
(a) Answer: Carbon dioxide and water vapour
(b) B1 volcanic activity / volcanoes (outgassing)
(b) Answer: Volcanic activity
(c) B1 as the Earth cooled, water vapour in the atmosphere condensed to form liquid water, which collected to form the oceans
(c) Answer: Water vapour condensed as the Earth cooled and collected to form the oceans.
Question 5
(a) B1 carbon dioxide + water -> glucose + oxygen (oe, correct order of reactants/products)
(a) Answer: Carbon dioxide + water -> glucose + oxygen
(b) M1 cyanobacteria (and later algae/plants) carried out photosynthesis, removing carbon dioxide and releasing oxygen as a waste product
(b) M1 over a very long period of time, oxygen was produced faster than it was removed, so it gradually built up in the atmosphere
(b) Answer: Photosynthesis by cyanobacteria released oxygen as a waste product; over hundreds of millions of years this oxygen accumulated because it was produced faster than it was used up.
(c) B1 oe, e.g. oxygen produced first reacted with substances in the oceans/rocks (e.g. dissolved iron) before it could accumulate in the atmosphere; or only small numbers of organisms were present at first so oxygen was released slowly
(c) Answer: Much of the early oxygen reacted with dissolved substances (e.g. iron) in the oceans and rocks before it could build up in the atmosphere.
Question 6
B1 the Sun's (shortwave) radiation passes through the atmosphere and warms the Earth's surface
B1 the warmed surface radiates (longwave) infrared radiation
B1 greenhouse gases (e.g. carbon dioxide, methane, water vapour) absorb this infrared radiation and re-radiate it in all directions, including back towards the Earth, keeping the surface warmer than it would otherwise be
Answer: The greenhouse effect is the natural warming of the Earth caused by greenhouse gases absorbing infrared radiation emitted by the warmed surface and re-radiating it back towards the surface, trapping heat in the atmosphere.
Question 7
(a) B1 carbon dioxide
(a) B1 methane (accept nitrous oxide)
(a) Answer: Carbon dioxide and methane
(b) M1 more greenhouse gas molecules are present, so more of the infrared radiation emitted by the Earth's surface is absorbed
(b) M1 more of this energy is re-radiated back towards the surface/trapped within the atmosphere-surface system, increasing average global temperature
(b) Answer: Higher concentrations of greenhouse gases absorb more outgoing infrared radiation and re-radiate more of it back towards the Earth, trapping extra energy and raising the average global temperature.
Question 8
(a) B1 415 - 315 = 100 ppm cao
(a) Answer: 100 ppm
(b) M1 100 ppm / 60 years (correct number of years used)
(b) A1 1.67 ppm per year awrt 1.67
(b) Answer: 1.67 ppm per year
(c) M1 (100 / 315) x 100
(c) A1 31.7% awrt 31.7%
(c) Answer: 31.7%
Question 9
B1 a correlation between two variables (CO2 concentration and temperature) does not on its own prove that one caused the other
B1 however, there is a well-understood scientific mechanism (the enhanced greenhouse effect) that explains how increased CO2 could cause warming, and other explanations (e.g. natural variation, changes in solar output) do not fully account for the size or speed of the observed warming
B1 so while correlation alone is not proof, the combination of correlation, a credible causal mechanism, and climate modelling gives scientists high confidence that rising CO2 is a major cause of the temperature rise, though not necessarily the only cause
Answer: The claim is only partly justified: correlation alone does not prove causation, but the existence of a credible mechanism (the enhanced greenhouse effect) and the elimination of other explanations means scientists are confident CO2 is a major, though not the sole, cause of the warming.
Question 10
(a) B1 620 + 32 = 652 kg CO2e cao
(a) Answer: 652 kg CO2e
(b) M1 Campbell family total = 620 + 6 = 626 kg CO2e
(b) A1 652 - 626 = 26 kg CO2e lower ft from (a)
(b) Answer: 26 kg CO2e lower
(c) M1 620 / 32 = approximately 19 (to the nearest whole number)
(c) A1 conclusion that this ratio (about 19 times) is much greater than the claimed 4 times, so the claim is not supported by this data
(c) Answer: The claim is not supported; the flight produces about 19 times more CO2e than the car journey, not 4 times.
Question 11
(a) B1 carbon dioxide
(a) Answer: Carbon dioxide
(b) B1 methane
(b) Answer: Methane
(c) B1 burning or decaying trees release stored carbon as CO2, and fewer trees remain to remove CO2 from the atmosphere by photosynthesis (both effects needed for the mark)
(c) Answer: Burning or rotting trees release the carbon they stored as CO2, and having fewer trees means less CO2 is removed from the atmosphere by photosynthesis.
(d) B1 methane
(d) Answer: Methane
Question 12
(a) M1 as sea water warms it expands (thermal expansion), increasing its volume
(a) M1 melting of land-based ice (glaciers and ice sheets) adds extra water to the oceans
(a) Answer: Warmer sea water expands (thermal expansion) and melting land ice adds more water to the oceans, both raising sea level.
(b) B1 any one from: more frequent/extreme weather events (storms, floods, droughts); changes to migration patterns or habitats of animals; changes to crop yields or growing seasons; loss of habitat, e.g. reduced Arctic sea ice affecting polar bears
(b) B1 a second, different valid effect from the same list
(b) Answer: e.g. more frequent extreme weather events, and changes to the migration patterns of animals.
Question 13
(a) B1 sulfur dioxide
(a) Answer: Sulfur dioxide
(b) B1 carbon monoxide
(b) Answer: Carbon monoxide
(c) B1 particulates / soot / particulate carbon
(c) Answer: Particulates (soot)
(d) B1 (oxides of) nitrogen / nitrogen oxides
(d) Answer: Nitrogen oxides
(e) B1 particulates reflect and/or absorb/scatter sunlight, reducing the amount of sunlight that reaches the Earth's surface (global dimming) (oe)
(e) Answer: Particulates reflect and scatter sunlight, reducing the amount that reaches the surface - an effect known as global dimming.
Question 14
(a) B1 cso: 16 + 64 = 80 and 44 + 36 = 80, so mass of reactants = mass of products
(a) Answer: 16 + 64 = 80 g of reactants; 44 + 36 = 80 g of products, so mass is conserved.
(b) M1 8 g is half of 16 g, so use the ratio 16 g methane : 44 g carbon dioxide, halved
(b) A1 22 g cao
(b) Answer: 22 g
(c) B1 32 g cao (half of 64 g)
(c) Answer: 32 g
Question 15
(a) M1 use conservation of mass: mass of oxygen = mass of magnesium oxide - mass of magnesium = 40 - 24
(a) A1 16 g cao
(a) Answer: 16 g
(b) B1 it was oxygen gas from the air surrounding the magnesium (oxygen makes up about 21% of the air) (oe)
(b) Answer: It came from oxygen gas in the surrounding air, which makes up about 21% of the atmosphere.
Question 16
Level 1 (1-2): Simple statements are made about climate change or human activity, with little or no linking of evidence to conclusions. Limited or no use of scientific terminology.
Level 2 (3-4): Some relevant evidence and human activities are described and linked to increasing greenhouse gas concentrations and/or rising temperature, with some reasoning. Discussion of ways to reduce CO2 concentration is mostly descriptive rather than evaluative. Scientific terminology is used with some accuracy.
Level 3 (5-6): A well-reasoned and detailed evaluation is given, using evidence (e.g. ice core data, direct atmospheric measurements, the timing of industrialisation) to support the conclusion that human activity is a major cause of recent warming, while acknowledging natural factors and the limits of the evidence. A range of appropriate methods to reduce atmospheric CO2 are discussed with reference to their effectiveness or limitations. Scientific terminology is used accurately throughout.
Indicative content:
Ice cores contain trapped air bubbles that allow scientists to measure past atmospheric CO2 concentrations and estimate past temperatures, going back hundreds of thousands of years.
These records show that CO2 concentration and global temperature have historically risen and fallen together (a correlation).
Since the industrial revolution (roughly 200-250 years ago), CO2 concentration has risen much faster than at any previous point shown by ice core data, closely matching the large-scale burning of fossil fuels.
The enhanced greenhouse effect provides a credible scientific mechanism directly linking rising CO2 and methane concentrations to rising average temperature.
Natural factors, such as volcanic activity and variation in the Sun's output, do affect temperature, but cannot fully account for the size or speed of the recent warming.
The strength and consistency of evidence from several independent sources (ice cores, direct atmospheric measurements since the 1950s, global temperature records) supports the conclusion that human activity is a major cause of recent warming.
Ways to reduce future CO2 concentration include: switching to renewable or low-carbon energy sources (wind, solar, nuclear) to reduce fossil fuel burning; improving energy efficiency and insulation to reduce energy demand; carbon capture and storage at power stations; reducing deforestation and increasing afforestation (planting trees) to increase CO2 removal; international agreements between governments to set emissions targets.
Each method has limitations (e.g. cost, scalability, reliability, time needed to implement), which should be weighed against its potential to reduce emissions.
Question 17
(a) B1 photosynthesis
(a) Answer: Photosynthesis
(b) B1 respiration
(b) Answer: Respiration
(c) B1 fossilisation / formation of fossil fuels (oe)
(c) Answer: Fossilisation (formation of fossil fuels)
(d) B1 combustion releases, within seconds, carbon that was locked away by living organisms and stored in fossil fuels over millions of years, so carbon is returned to the atmosphere far faster than it was originally removed (oe)
(d) Answer: Combustion releases carbon almost instantly, whereas that carbon took millions of years to become locked away in fossil fuels, so it returns to the atmosphere far faster than it was removed.
Question 18
B1 valid method 1, e.g. insulate the home (loft/wall insulation) or install solar panels/use a renewable electricity tariff or walk/cycle/use public transport instead of driving or eat less meat
B1 linked explanation for method 1 showing how it reduces greenhouse gas emissions (oe)
B1 valid method 2, different from method 1
B1 linked explanation for method 2 showing how it reduces greenhouse gas emissions (oe)
Answer: e.g. (1) Insulate the home, because this reduces the amount of gas needed for heating, cutting CO2 emissions from burning fuel. (2) Use a renewable electricity tariff, because this generates electricity without burning fossil fuels, cutting CO2 emissions.
Question 19
B1 as snow fell and compacted into ice over thousands of years, tiny bubbles of the atmosphere at that time became trapped and sealed inside the ice
B1 scientists can analyse the trapped air in these bubbles at different depths to directly measure the CO2 concentration of the atmosphere when that layer formed, with deeper ice being older
B1 the ratio of oxygen isotopes in the ice itself changes depending on the temperature at the time the ice formed, so scientists use this ratio to estimate past temperatures
Answer: Trapped air bubbles in the ice directly record past atmospheric CO2 concentration, while the ratio of oxygen isotopes in the ice itself is used to estimate the temperature at the time each layer formed.