Earth and the atmosphere: GCSE questions with answers
21 chemistry questions on earth and the atmosphere. Pick your answer, then tap to see if you were right and why. Every answer comes from the Show Working science bank, checked against the GCSE content every board in England teaches.
Choose your answer before you open it. Then read why, so it sticks.
01 / Earth and the atmosphereBoth tiers
Where are the gases of the Earth’s early atmosphere thought to have come from?
AVolcanoes
BThe oceans
CPhotosynthesis
DBurning fossil fuels
Show the answer
Answer: A Volcanoes
One theory is that intense volcanic activity in the Earth’s first billion years released the gases of the early atmosphere: mainly carbon dioxide, with water vapour, some nitrogen and little or no oxygen, rather like the atmospheres of Mars and Venus today.
As the Earth cooled, water vapour from volcanoes condensed to form the oceans. Evidence is limited because this happened billions of years ago, so scientists use clues such as the gases volcanoes give out today and the atmospheres of other planets.
How was much carbon dioxide removed from the early atmosphere before algae and plants existed?
APlants used it in photosynthesis
BIt escaped into space
CIt dissolved in the oceans
DAnimals breathed it in
Show the answer
Answer: C It dissolved in the oceans
Carbon dioxide fell in several ways. As the oceans formed it dissolved in the water, and carbonates precipitated to form sediments and later limestone. Later, algae and plants used it in photosynthesis, and some carbon was locked into fossil fuels such as coal, crude oil and natural gas.
Where did the oxygen in today’s atmosphere come from?
APhotosynthesis by algae and plants
BVolcanoes releasing it
CRespiration by animals
DWater evaporating from the oceans
Show the answer
Answer: A Photosynthesis by algae and plants
Algae, and later plants, made the oxygen now in the atmosphere by photosynthesis: carbon dioxide + water → glucose + oxygen. Over hundreds of millions of years the oxygen built up until there was enough for animals to evolve.
Today the air is about four-fifths nitrogen and about one-fifth oxygen, with small amounts of argon and other noble gases, carbon dioxide and water vapour. Carbon dioxide makes up only a tiny fraction of the air.
What kind of radiation do greenhouse gases absorb?
AVisible light coming in from the Sun
BRadio waves from the Earth’s core
CUltraviolet radiation from the ozone layer
DInfrared radiation given out by the Earth
Show the answer
Answer: D Infrared radiation given out by the Earth
Short-wavelength radiation from the Sun passes through the atmosphere and warms the surface. The Earth gives out longer-wavelength infrared radiation. Greenhouse gases absorb some of it and re-emit it in all directions, some back towards the Earth, which keeps the Earth warmer than it would otherwise be.
Carbon dioxide, methane and water vapour are greenhouse gases; nitrogen and oxygen are not. A natural greenhouse effect keeps the Earth warm enough for life. The problem is that extra greenhouse gases from human activity are making the effect stronger.
Which human activity adds the most carbon dioxide to the atmosphere?
ABurning fossil fuels
BPlanting trees
CBreathing out
DUsing wind turbines
Show the answer
Answer: A Burning fossil fuels
Burning fossil fuels and deforestation add carbon dioxide to the air: fuels release it when they burn, and fewer trees remove it by photosynthesis. Cattle farming, rice fields and rotting waste in landfill sites add methane.
A graph shows carbon dioxide levels and fossil fuel use both rising since 1850. What does the graph show on its own?
AThat carbon dioxide is falling
BThat they are not linked at all
CProof that one causes the other
DA correlation between them
Show the answer
Answer: D A correlation between them
Carbon dioxide levels have risen since the Industrial Revolution, matching the rise in fossil fuel use and in global temperature. A correlation alone does not prove a cause, but it fits how greenhouse gases are known to behave, and peer-reviewed evidence from many studies supports the link.
Why are there uncertainties in predicting the future climate?
ACarbon dioxide does not absorb infrared
BThe climate system is very complex
CClimate models are never tested
DTemperatures have never been measured
Show the answer
Answer: B The climate system is very complex
The evidence has uncertainties: the climate is complex, so models simplify it; older records had fewer, less accurate measurements from fewer places; and where readings are taken matters, as cities are warmer than the land around them. Natural changes also affect the climate.
Which is an effect of climate change caused by extra greenhouse gases?
AA thinner crust
BSea levels rising
CMore tsunamis
DMore earthquakes
Show the answer
Answer: B Sea levels rising
Extra greenhouse gases are raising the average global temperature. Effects include rising sea levels from melting land ice and warming water, more frequent and severe storms, changes in the amount and pattern of rainfall, changes in where food can be grown and changes to where wildlife can live.
Ways to reduce the effects include using renewable or nuclear energy instead of fossil fuels, saving energy, carbon capture and storage, planting trees, and taxes or limits on emissions. Each must be weighed up for its scale, risks, cost and environmental impact, such as land use or leaks of stored gas.
Why is it hard to reduce greenhouse gas emissions worldwide?
ARenewable energy has not been invented
BGreenhouse gases cannot be measured
CEvery country needs to agree and act
DNobody produces greenhouse gases
Show the answer
Answer: C Every country needs to agree and act
Reducing emissions is hard because it needs international agreement, people may not want to change their lifestyles, some countries worry about the cost to their economies and industries, and not everyone has clear information.
Answer: B Incomplete combustion in too little oxygen
Carbon monoxide forms when a fuel containing carbon burns in too little oxygen (incomplete combustion). It is toxic: it combines with haemoglobin, so the blood carries less oxygen. It is colourless and odourless, so it is not easily detected.
Particulates are tiny solid particles, such as soot (carbon) and unburnt hydrocarbons, released mainly by incomplete combustion, for example in diesel engines. They reflect sunlight, causing global dimming, and can be breathed deep into the lungs, causing health problems.
Many fuels, especially coal and some oils, contain sulfur impurities. When the fuel burns, the sulfur reacts with oxygen to make sulfur dioxide. It dissolves in rain water to cause acid rain, which damages buildings, plants and lakes, and it causes breathing problems.
In a car engine, where does the nitrogen in oxides of nitrogen come from?
AThe air
BThe exhaust pipe
CThe fuel
DThe engine oil
Show the answer
Answer: A The air
At the high temperature inside an engine, nitrogen and oxygen from the air react to make oxides of nitrogen. Like sulfur dioxide, they cause acid rain and breathing problems. The nitrogen comes from the air, not from the fuel.
Potable water is water that is safe to drink: it has low levels of dissolved salts and microbes. It is not pure in the chemical sense, because it still contains dissolved substances such as small amounts of salts.
In the UK most drinking water comes from rain that collects in the ground, lakes and rivers. A suitable source is chosen, solids are allowed to settle and the water is filtered to remove particles, then it is sterilised, for example with chlorine, to kill microbes.
Which method can turn sea water into potable water?
AChlorination
BDistillation
CFiltration
DChromatography
Show the answer
Answer: B Distillation
Sea water contains a lot of dissolved salt, which filtration cannot remove. Distillation boils the water and condenses the steam, leaving the salt behind. Removing salt needs large amounts of energy, so it is used where fresh water is scarce.
Which source of water is usually easiest to make potable?
AWaste water from homes
BSea water
CWater from a factory drain
DGround water
Show the answer
Answer: D Ground water
Ground water is usually the easiest to treat: it has been filtered as it passed through rock. Waste water contains organic matter and harmful microbes, so it needs more stages. Salt water needs desalination, which uses a lot of energy.
Describe how scientists think the Earth’s early atmosphere changed to become the atmosphere we have today.
What a full answer includes
Volcanoes released gases that formed the early atmosphere: mainly carbon dioxide, with water vapour and nitrogen, and perhaps small amounts of methane and ammonia.
There was little or no oxygen in the early atmosphere.
As the Earth cooled, water vapour condensed to form the oceans.
Carbon dioxide dissolved in the oceans, and carbonates were precipitated as sediments, removing carbon dioxide.
Algae and later plants used carbon dioxide in photosynthesis and released oxygen.
Oxygen gradually built up in the atmosphere.
Carbon was locked away in sedimentary rocks such as limestone and in fossil fuels.
Nitrogen built up, so today the air is about four-fifths nitrogen and one-fifth oxygen, with small amounts of other gases.
Model answer
Scientists think that during the Earth’s first billion years there was intense volcanic activity, and the volcanoes released the gases that formed the early atmosphere. This was mainly carbon dioxide, with water vapour and nitrogen, and possibly small amounts of methane and ammonia, but there was little or no oxygen. As the Earth cooled, the water vapour condensed to form the oceans. A lot of carbon dioxide dissolved in the oceans, and carbonates were precipitated, forming sediments, which reduced the carbon dioxide in the air. Later, algae, and then plants, evolved. They took in carbon dioxide for photosynthesis and gave out oxygen, so the amount of carbon dioxide fell further and oxygen slowly built up in the atmosphere, which allowed animals to evolve. Carbon from living things was locked away in sedimentary rocks such as limestone and in fossil fuels such as coal, oil and natural gas. Meanwhile nitrogen, which is unreactive, gradually built up. Today the atmosphere is about four-fifths nitrogen and one-fifth oxygen, with small amounts of argon, carbon dioxide and water vapour.
Where marks slip
Some answers have plants removing carbon dioxide from the very start, before they existed. Keep the order: volcanoes, oceans forming and dissolving carbon dioxide, then algae and plants making oxygen.
6 marks / Evidence for human-caused climate changeBoth tiers
Around 1850, carbon dioxide made up about 280 parts per million of the air. Today it is more than 420 parts per million, and over the same time the Earth’s average surface temperature has risen by more than 1 °C. Early temperature records came from fewer places than today, mostly on land.
Explain how greenhouse gases keep the Earth warm, and evaluate the evidence that human activity is causing climate change.
What a full answer includes
Short wavelength radiation from the Sun passes through the atmosphere and warms the Earth’s surface.
The Earth gives out longer wavelength (infrared) radiation.
Greenhouse gases such as carbon dioxide, methane and water vapour absorb this radiation and re-emit it in all directions, some back towards the Earth, which keeps it warm.
Burning fossil fuels releases carbon dioxide, and farming and landfill release methane.
The rise in carbon dioxide matches the rise in burning fossil fuels and the rise in temperature (a correlation).
There is a known mechanism, the greenhouse effect, that explains how more carbon dioxide causes warming.
Uncertainties: early records came from fewer places and were less accurate, and the climate is complex and hard to model.
Most scientists, in peer-reviewed work, conclude that human activity is the main cause: a justified conclusion.
Model answer
Radiation from the Sun, which is mostly short wavelength, passes through the atmosphere and is absorbed by the Earth’s surface, warming it. The warm Earth then gives out longer wavelength, infrared radiation. Greenhouse gases in the atmosphere, such as carbon dioxide, methane and water vapour, absorb some of this infrared radiation and re-emit it in all directions, including back towards the Earth, so the lower atmosphere stays warmer than it would otherwise be. Human activities add more of these gases: burning fossil fuels releases carbon dioxide, and cattle farming, rice fields and landfill sites release methane. The data show carbon dioxide rising by about half since 1850, at the same time as fossil fuel use grew and the average temperature rose by more than 1 °C. A correlation alone does not prove one thing causes another, but here there is a clear mechanism, the greenhouse effect, that explains how more carbon dioxide traps more energy. There are uncertainties: early temperatures were measured in fewer places and less accurately, and the climate is so complex that models are simplified. Even so, peer-reviewed studies by most climate scientists agree, so the evidence that human activity is the main cause is strong.
Where marks slip
Blaming the hole in the ozone layer, or saying greenhouse gases “trap heat” with no mention of absorbing and re-emitting infrared radiation, loses marks. Evaluating also means naming the uncertainties.
03 / In the appComing to Show Working
All 34 earth and the atmosphere facts in Show Working
In the app, choose your exam board and course and you only see what your board asks for. Tap through questions, or open Read the answers to see every answer in the topic at once, covered until you tap. Science is coming to the app soon.
Show Working
