Chemistry of the atmosphere
50 exam-style questions with answers for 4.9 Chemistry of the atmosphere in AQA GCSE Chemistry (spec 8462). Practise with flashcards, a topic quiz, a random quiz across the course, 5 crosswords, or read every question and answer below.
All 50 questions and answers
Question 1 · Spec 4.9.1.1 · Atmosphere
State the approximate proportions of nitrogen and oxygen in today's atmosphere. [2 marks]
Answer:About four-fifths (80%) nitrogen (1); about one-fifth (20%) oxygen (1).Question 2 · Spec 4.9.1.1 · Atmosphere
Name three gases found in small proportions in the atmosphere. [3 marks]
Answer:Carbon dioxide (1); water vapour (1); noble gases such as argon (1).Question 3 · Spec 4.9.1.1 · Atmosphere
For how long has the composition of the atmosphere been about the same as today? [1 mark]
Answer:About 200 million years.Question 4 · Spec 4.9.1.2 · Early atmosphere
Describe one theory of the Earth's early atmosphere. [2 marks]
Answer:Intense volcanic activity released gases (1); mainly carbon dioxide with little or no oxygen, like Mars and Venus today (1).Question 5 · Spec 4.9.1.2 · Early atmosphere
Where did the water in the oceans come from? [1 mark]
Answer:Water vapour from volcanoes condensed as the Earth cooled.Question 6 · Spec 4.9.1.2 · Early atmosphere
Why is evidence for the early atmosphere limited? [1 mark]
Answer:It was billions of years ago, so there is little direct evidence.Question 7 · Spec 4.9.1.2 · Early atmosphere
Name two other gases volcanoes may have released. [2 marks]
Answer:Any two from: nitrogen (1); small amounts of methane (1); ammonia (1).Question 8 · Spec 4.9.1.3 · Oxygen
How did oxygen levels in the atmosphere increase? [2 marks]
Answer:Algae and plants evolved and carried out photosynthesis (1); which uses carbon dioxide and releases oxygen (1).Question 9 · Spec 4.9.1.3 · Oxygen
When did algae first produce oxygen? [1 mark]
Answer:About 2.7 billion years ago.Question 10 · Spec 4.9.1.3 · Photosynthesis
Write the word equation for photosynthesis. [1 mark]
Answer:Carbon dioxide + water → glucose + oxygen.Question 11 · Spec 4.9.1.4 · Carbon dioxide
State three ways the amount of carbon dioxide in the early atmosphere decreased. [3 marks]
Answer:It dissolved in the oceans and formed carbonate sediments (1); plants and algae absorbed it by photosynthesis (1); it was locked up in sedimentary rocks such as limestone and fossil fuels (1).Question 12 · Spec 4.9.1.4 · Fossil fuels
How was coal formed? [1 mark]
Answer:From thick deposits of plant material buried and compressed over millions of years.Question 13 · Spec 4.9.2.1 · Greenhouse gases
Name three greenhouse gases. [3 marks]
Answer:Water vapour (1); carbon dioxide (1); methane (1).Question 14 · Spec 4.9.2.1 · Greenhouse effect
Explain the greenhouse effect. [3 marks]
Answer:Short-wavelength radiation from the Sun passes through the atmosphere and warms the Earth (1); the Earth emits longer-wavelength infrared radiation (1); greenhouse gases absorb and re-emit it, keeping the Earth warm (1).Question 15 · Spec 4.9.2.2 · Human activity
State two human activities that increase carbon dioxide levels. [2 marks]
Answer:Any two from: burning fossil fuels (1); deforestation (1); cement production (1).Question 16 · Spec 4.9.2.2 · Human activity
State two human activities that increase methane levels. [2 marks]
Answer:Any two from: cattle farming (1); rice paddy fields (1); landfill sites (1).Question 17 · Spec 4.9.2.2 · Climate change
Why do some people doubt that humans cause climate change? [2 marks]
Answer:Any two from: the climate is complex and hard to model (1); simplified models and media speculation can be misleading (1); natural changes have happened in the past (1).Question 18 · Spec 4.9.2.2 · Peer review
Why is evidence on climate change peer reviewed? [1 mark]
Answer:So other scientists check the evidence and methods before it is accepted.Question 19 · Spec 4.9.2.3 · Climate change
State four possible effects of global climate change. [4 marks]
Answer:Any four from: sea level rise causing flooding (1); more extreme weather such as storms (1); changes in rainfall and water supply (1); changes in food production (1); changes in the distribution of wildlife species (1).Question 20 · Spec 4.9.2.4 · Carbon footprint
Define carbon footprint. [1 mark]
Answer:The total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event.Question 21 · Spec 4.9.2.4 · Carbon footprint
State three ways to reduce a carbon footprint. [3 marks]
Answer:Any three from: using renewable energy (1); energy conservation (1); carbon capture and storage (1); carbon taxes and licences (1); carbon offsetting, e.g. planting trees (1).Question 22 · Spec 4.9.2.4 · Carbon footprint
State two problems in reducing carbon footprints. [2 marks]
Answer:Any two from: scientific disagreement about causes and effects (1); lack of public information and education (1); lifestyle changes people resist (1); economic considerations (1).Question 23 · Spec 4.9.3.1 · Pollutants
Name three pollutants produced when fuels burn. [3 marks]
Answer:Carbon monoxide (1); sulfur dioxide (1); oxides of nitrogen (1).Question 24 · Spec 4.9.3.1 · Incomplete combustion
What is produced by incomplete combustion? [2 marks]
Answer:Carbon monoxide (1); soot (carbon particulates) (1).Question 25 · Spec 4.9.3.1 · Sulfur dioxide
Where does sulfur dioxide come from? [1 mark]
Answer:The combustion of fuels that contain sulfur impurities.Question 26 · Spec 4.9.3.1 · Nitrogen oxides
How are oxides of nitrogen formed in car engines? [1 mark]
Answer:Nitrogen and oxygen from the air react at the high temperatures in the engine.Question 27 · Spec 4.9.3.2 · Carbon monoxide
Why is carbon monoxide dangerous? [2 marks]
Answer:It is toxic, preventing the blood from carrying oxygen (1); it is colourless and odourless, so it is hard to detect (1).Question 28 · Spec 4.9.3.2 · Acid rain
What problems are caused by sulfur dioxide and oxides of nitrogen? [2 marks]
Answer:They cause respiratory problems (1); and acid rain (1).Question 29 · Spec 4.9.3.2 · Particulates
What problems are caused by particulates? [2 marks]
Answer:Global dimming (1); and health problems for humans, such as lung damage (1).Question 30 · Spec 4.9.1.1 · Atmosphere
Which gas makes up about 0.04% of the atmosphere? [1 mark]
Answer:Carbon dioxide.Question 31 · Spec 4.9.2.1 · Greenhouse gases
Why are greenhouse gases needed? [1 mark]
Answer:They keep the Earth warm enough to support life.Question 32 · Spec 4.9.2.3 · Climate change
Why might rising sea levels be a problem? [1 mark]
Answer:Low-lying coastal areas and islands would flood.Question 33 · Spec 4.9.1.4 · Limestone
How was limestone formed? [1 mark]
Answer:From the shells and skeletons of marine organisms, made of calcium carbonate.Question 34 · Spec 4.9.1.4 · Crude oil
How were crude oil and natural gas formed? [1 mark]
Answer:From deposits of plankton buried in mud and compressed over millions of years.Question 35 · Spec 4.9.2.2 · Human activity
Why does deforestation increase carbon dioxide levels? [2 marks]
Answer:Fewer trees absorb carbon dioxide by photosynthesis (1); and trees burnt to clear land release carbon dioxide (1).Question 36 · Spec 4.9.3.1 · Complete combustion
Write the word equation for the complete combustion of methane. [1 mark]
Answer:Methane + oxygen → carbon dioxide + water.Question 37 · Spec 4.9.3.1 · Incomplete combustion
Why does incomplete combustion happen? [1 mark]
Answer:There is not enough oxygen for the fuel to burn completely.Question 38 · Spec 4.9.2.4 · Carbon capture
What is carbon capture and storage? [1 mark]
Answer:Collecting carbon dioxide from power stations and storing it underground, for example in old oil fields.Question 39 · Spec 4.9.3.2 · Acid rain
State one effect of acid rain on the environment. [1 mark]
Answer:It damages trees, kills fish in lakes, or corrodes buildings and statues.Question 40 · Spec 4.9.1.2 · Early atmosphere
Why are Mars and Venus used as evidence for the Earth's early atmosphere? [1 mark]
Answer:Their atmospheres today are mainly carbon dioxide, which may be like the Earth's early atmosphere.Question 41 · Spec 4.9.2.1 · Greenhouse effect
What type of radiation do greenhouse gases absorb? [1 mark]
Answer:Long-wavelength (infrared) radiation emitted by the Earth.Question 42 · Spec 4.9.2.3 · Climate change
What is global climate change? [1 mark]
Answer:Long-term changes in the Earth's climate, including rising average temperatures.Question 43 · Spec 4.9.3.2 · Sulfur dioxide
How can sulfur dioxide emissions be reduced? [1 mark]
Answer:Remove sulfur from fuels before burning, or use scrubbers in power station chimneys.Question 44 · Spec 4.9.3.2 · Nitrogen oxides
How do catalytic converters reduce pollution? [1 mark]
Answer:They convert carbon monoxide and oxides of nitrogen into carbon dioxide and nitrogen.Question 45 · Spec 4.9.2.4 · Carbon footprint
Why are carbon taxes used? [1 mark]
Answer:To encourage companies and people to reduce emissions by making polluting more expensive.Question 46 · Spec 4.9.1.3 · Oxygen
Why did oxygen levels increase slowly at first? [1 mark]
Answer:Early oxygen reacted with iron and other substances in rocks and oceans before building up in the air.Question 47 · Spec 4.9.2.2 · Human activity
Why has the amount of methane increased? [1 mark]
Answer:More cattle farming, rice growing and landfill as the population has grown.Question 48 · Spec 4.9.3.1 · Particulates
What are particulates? [1 mark]
Answer:Tiny solid particles, such as soot, released when fuels burn.Question 49 · Spec 4.9.2.1 · Greenhouse gases
Is nitrogen a greenhouse gas? [1 mark]
Answer:No; it does not absorb infrared radiation.Question 50 · Spec 4.9.2.2 · Human activity
Why has the percentage of carbon dioxide in the atmosphere increased over the last 150 years? [1 mark]
Answer:Burning more fossil fuels since the Industrial Revolution, and deforestation.