Define the term atmosphere in the context of early Earth.

The atmosphere is the layer of gases surrounding the Earth, held in place by gravity. It formed from gases released by volcanic eruptions early in Earth's history.

True or False? The early Earth's atmosphere contained a high proportion of oxygen.

False. The early atmosphere contained mainly carbon dioxide and water vapour with little or no oxygen present.

How did volcanoes contribute to the formation of Earth's early atmosphere?

Volcanoes erupted and released gases from the Earth's interior, including carbon dioxide , water vapour , nitrogen, hydrogen, ammonia and methane. Earth's gravity prevented these gases from escaping into space, so they accumulated to form the atmosphere.

When the early Earth cooled sufficiently, water vapour .......... and fell to the surface, forming the oceans .

When the early Earth cooled sufficiently, water vapour condensed and fell to the surface, forming the oceans .

Why did the amount of carbon dioxide in the early atmosphere decrease as the oceans formed?

Carbon dioxide is water soluble , so large amounts dissolved into the oceans as they formed. Carbonate substances then precipitated and settled as sediments, locking the carbon dioxide away.

True or False? Primitive plants and algae increased the level of oxygen in the atmosphere through photosynthesis.

True. Primitive plants and algae used up carbon dioxide and released oxygen through photosynthesis , gradually building up the oxygen-rich atmosphere we have today.

Define photosynthesis and state its role in changing the atmosphere.

Photosynthesis is the process by which plants and algae use sunlight, carbon dioxide and water to produce glucose and oxygen . It was the key process that increased atmospheric oxygen levels over billions of years.

What is the approximate composition of Earth's atmosphere today?

The atmosphere is approximately 20% oxygen and 80% nitrogen , with trace amounts of other gases including carbon dioxide and noble gases.

Marine algae are thought to be responsible for about .......... % of all atmospheric oxygen produced.

Marine algae are thought to be responsible for about 90 % of all atmospheric oxygen produced.

How did Earth's atmosphere develop from the early atmosphere to its current composition?

The early atmosphere was mainly carbon dioxide and water vapour with little oxygen. As Earth cooled, water vapour condensed to form the oceans, dissolving much of the CO 2 . Over billions of years, photosynthesis by plants and algae steadily increased oxygen levels and reduced CO 2 , reaching the current composition around 200 million years ago.

Define greenhouse gases .

Greenhouse gases are gases in the atmosphere that absorb and trap infrared radiation emitted from the Earth's surface, preventing it from escaping into space. Examples include carbon dioxide , methane and water vapour .

Describe how the greenhouse effect keeps the Earth warm.

Shortwave radiation from the Sun is absorbed by the Earth's surface and re-emitted as infrared radiation. Greenhouse gases in the atmosphere absorb and trap this infrared radiation, preventing heat from escaping into space and keeping the Earth at a habitable temperature.

True or False? Without any greenhouse gases, the Earth's surface temperature would be stable and comfortable.

False. Without greenhouse gases the Earth's surface would swing between extreme heat and extreme cold rather than maintaining the stable mean temperature of around 15°C that supports life.

The three main greenhouse gases are carbon dioxide, .......... and water vapour.

The three main greenhouse gases are carbon dioxide, methane and water vapour.

Distinguish between the greenhouse effect and the enhanced greenhouse effect .

The greenhouse effect is the natural process that maintains the Earth's mean temperature at around 15°C. The enhanced greenhouse effect is the additional warming caused by increased concentrations of greenhouse gases due to human activity.

Give two sources of carbon dioxide that contribute to the greenhouse effect.

The combustion of wood and fossil fuels.\n2. The respiration of plants and animals.\n\nIt is also produced by thermal decomposition of carbonate rocks and by the reaction of acids with carbonates.

True or False? Methane is released into the atmosphere by the digestive processes of animals.

True. Methane is produced by the digestive processes of animals, as well as by decomposition of vegetation and bacterial action in swamps and rice paddy fields.

Why are increasing levels of carbon dioxide and methane a concern, even though they are present in only small amounts?

Even in small amounts, carbon dioxide and methane are effective at absorbing and trapping infrared radiation . Rising concentrations are causing the enhanced greenhouse effect , which is leading to global warming and climate change.

Infrared radiation emitted from the Earth's surface is .......... by greenhouse gases, preventing it from escaping into space.

Infrared radiation emitted from the Earth's surface is absorbed by greenhouse gases, preventing it from escaping into space.

Define climate change .

Climate change is a long-term shift in worldwide weather patterns and conditions, largely driven by rising levels of greenhouse gases in the atmosphere.

Explain how burning fossil fuels contributes to climate change.

Burning fossil fuels releases carbon dioxide into the atmosphere. Carbon dioxide is a greenhouse gas that traps heat, leading to the enhanced greenhouse effect and rising global temperatures, which drive climate change .

True or False? Deforestation increases the amount of carbon dioxide in the atmosphere.

True. Trees remove CO 2 during photosynthesis . Removing them reduces this uptake, so more CO 2 remains in the atmosphere, enhancing the greenhouse effect .

Increasing agricultural activity and landfill sites contribute to climate change by releasing more .......... into the atmosphere.

Increasing agricultural activity and landfill sites contribute to climate change by releasing more methane into the atmosphere.

Why is historical climate data less reliable than modern measurements?

Historical data was collected without accurate instruments and from fewer locations . Scientists use indirect methods such as ice cores , tree rings and the fossil record to estimate past conditions, but these are less precise than modern techniques.

True or False? The majority of climate scientists believe that human activity is causing climate change.

True. Academic surveys show that around 97% of climate scientists agree that human activity is the primary cause of current climate change .

Give two consequences of rising global temperatures caused by climate change.

Melting of polar ice caps , leading to higher sea levels.\n2. More frequent and intense droughts that damage crop production. Storms and extreme heat waves are also becoming more common.

Define climate mitigation .

Climate mitigation refers to strategies that adapt to a changing climate rather than preventing it, such as building flood defences, changing crop types and redesigning infrastructure to withstand extreme weather.

Analysis of gas bubbles trapped in .......... allows scientists to estimate past climate conditions.

Analysis of gas bubbles trapped in ice cores allows scientists to estimate past climate conditions.

How does rising sea level threaten coastal areas?

Rising sea levels cause erosion of coastal land, flooding of wetlands and habitat destruction for wildlife. Low-lying cities face increased flooding and permanent loss of land without expensive barrier systems.

Define incomplete combustion .

Incomplete combustion occurs when there is insufficient oxygen for a fuel to burn fully, producing carbon monoxide , soot (carbon particulates) and water instead of carbon dioxide and water .

Why is carbon monoxide particularly dangerous as an atmospheric pollutant?

Carbon monoxide is colourless and odourless , making it impossible to detect without a monitor. It binds to haemoglobin in the blood, preventing it from carrying oxygen, which can cause fainting, coma or death.

True or False? Sulfur dioxide is produced from the complete combustion of fuels that contain sulfur.

True. \n\nFossil fuels contain small quantities of sulfur . When they burn, the sulfur is oxidised to produce sulfur dioxide , which is a major cause of acid rain .

Sulfur dioxide dissolves in rainwater to form .......... rain, which corrodes metal structures and harms aquatic life.

Sulfur dioxide dissolves in rainwater to form acid rain, which corrodes metal structures and harms aquatic life.

State two problems caused by soot particles released during incomplete combustion.

Soot causes respiratory problems by irritating the lungs.\n2. It covers buildings and statues, making them appear dark and dirty, and accelerates corrosion of surfaces.

True or False? Oxides of nitrogen are produced only from the combustion of fuels that contain nitrogen compounds.

False. Oxides of nitrogen are produced mainly from vehicle exhausts as a result of the high-temperature reaction between nitrogen and oxygen in the air during combustion — not solely from nitrogen compounds in the fuel.

Name four key pollutant gases produced by the combustion of fossil fuels.

Carbon dioxide \n2. Carbon monoxide \n3. Oxides of nitrogen \n4. Oxides of sulfur

Oxides of nitrogen from vehicle exhausts contribute to acid rain and also produce photochemical .......... .

Oxides of nitrogen from vehicle exhausts contribute to acid rain and also produce photochemical smog .

Explain why complete combustion is preferred over incomplete combustion in terms of safety and environmental impact.

Complete combustion produces only carbon dioxide and water, whereas incomplete combustion produces poisonous carbon monoxide and soot . Carbon monoxide is toxic and soot causes respiratory and environmental damage, making incomplete combustion more harmful.

What is the main source of atmospheric pollutants?

The main source is the combustion of fossil fuels . Incomplete combustion also produces unburned hydrocarbons and carbon particulates in addition to pollutant gases.

Define potable water .

Potable water is water that has been processed and is safe for human consumption and daily use. It may contain dissolved minerals and salts but must be free of harmful bacteria.

What is the difference between pure water and potable water?

Pure water consists solely of H 2 O molecules with no dissolved substances. Potable water may contain dissolved minerals and salts but has been treated to make it safe to drink.

True or False? Potable water must have a pH between 6.5 and 8.5.

True. \n\nPotable water must meet several standards, including a pH between 6.5 and 8.5 , very low levels of dissolved substances , and freedom from harmful bacteria .

Water stored in porous underground rocks is called .......... and the water it holds is known as groundwater.

Water stored in porous underground rocks is called an aquifer and the water it holds is known as groundwater.

Describe the two main steps used to treat fresh water and make it potable.

Filtration removes debris such as soil, grit and small particles using mesh screens followed by sand and gravel beds. Sterilisation then kills bacteria and microbes using chlorine gas, ultraviolet light or ozone.

True or False? Desalination is a cheap and energy-efficient method for producing potable water on a large scale.

False. \n\n Desalination is an expensive process that consumes large amounts of energy, making it unsuitable as a primary large-scale method. It is used in regions with very hot climates and limited fresh water, such as Saudi Arabia.

Define desalination .

Desalination is the process of removing salt from seawater to produce potable water, carried out by distillation or reverse osmosis using semi-permeable membranes.

How does reverse osmosis produce potable water from seawater?

Seawater is forced through a semi-permeable membrane under pressure. Only water molecules are small enough to pass through the membrane, leaving behind dissolved salts and other ions so that fresh water is collected on the other side.

During water treatment, .......... gas, ultraviolet light or ozone can be used to kill harmful bacteria in the water.

During water treatment, chlorine gas, ultraviolet light or ozone can be used to kill harmful bacteria in the water.

Why does the source of fresh water vary depending on the local climate?

In warmer areas, surface water evaporates before it can be collected, so water is found mainly in underground aquifers . In cooler or wetter regions, surface water from reservoirs, lakes and rivers is more readily available for treatment.

GCSEChemistryOCRChemistry A (Gateway)Flashcards6.Global ChallengesInterpreting & Interacting with Earth Systems

Interpreting & Interacting with Earth Systems (OCR GCSE Chemistry A (Gateway)): Flashcards

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FrontOrigins of the Atmosphere
Define the term atmosphere in the context of early Earth.

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Cards in this collection (49)

Define the term atmosphere in the context of early Earth.
The atmosphere is the layer of gases surrounding the Earth, held in place by gravity. It formed from gases released by volcanic eruptions early in Earth's history.
True or False?
The early Earth's atmosphere contained a high proportion of oxygen.
False.
The early atmosphere contained mainly carbon dioxide and water vapour with little or no oxygen present.
How did volcanoes contribute to the formation of Earth's early atmosphere?
Volcanoes erupted and released gases from the Earth's interior, including carbon dioxide, water vapour, nitrogen, hydrogen, ammonia and methane. Earth's gravity prevented these gases from escaping into space, so they accumulated to form the atmosphere.
When the early Earth cooled sufficiently, water vapour .......... and fell to the surface, forming the oceans.
When the early Earth cooled sufficiently, water vapour condensed and fell to the surface, forming the oceans.
Why did the amount of carbon dioxide in the early atmosphere decrease as the oceans formed?
Carbon dioxide is water soluble, so large amounts dissolved into the oceans as they formed. Carbonate substances then precipitated and settled as sediments, locking the carbon dioxide away.
True or False?
Primitive plants and algae increased the level of oxygen in the atmosphere through photosynthesis.
True.
Primitive plants and algae used up carbon dioxide and released oxygen through photosynthesis, gradually building up the oxygen-rich atmosphere we have today.
Define photosynthesis and state its role in changing the atmosphere.
Photosynthesis is the process by which plants and algae use sunlight, carbon dioxide and water to produce glucose and oxygen. It was the key process that increased atmospheric oxygen levels over billions of years.
What is the approximate composition of Earth's atmosphere today?
The atmosphere is approximately 20% oxygen and 80% nitrogen, with trace amounts of other gases including carbon dioxide and noble gases.
Marine algae are thought to be responsible for about ..........% of all atmospheric oxygen produced.
Marine algae are thought to be responsible for about 90% of all atmospheric oxygen produced.
How did Earth's atmosphere develop from the early atmosphere to its current composition?
The early atmosphere was mainly carbon dioxide and water vapour with little oxygen. As Earth cooled, water vapour condensed to form the oceans, dissolving much of the CO₂. Over billions of years, photosynthesis by plants and algae steadily increased oxygen levels and reduced CO₂, reaching the current composition around 200 million years ago.
Define greenhouse gases.
Greenhouse gases are gases in the atmosphere that absorb and trap infrared radiation emitted from the Earth's surface, preventing it from escaping into space. Examples include carbon dioxide, methane and water vapour.
Describe how the greenhouse effect keeps the Earth warm.
Shortwave radiation from the Sun is absorbed by the Earth's surface and re-emitted as infrared radiation. Greenhouse gases in the atmosphere absorb and trap this infrared radiation, preventing heat from escaping into space and keeping the Earth at a habitable temperature.
True or False?
Without any greenhouse gases, the Earth's surface temperature would be stable and comfortable.
False.
Without greenhouse gases the Earth's surface would swing between extreme heat and extreme cold rather than maintaining the stable mean temperature of around 15°C that supports life.
The three main greenhouse gases are carbon dioxide, .......... and water vapour.
The three main greenhouse gases are carbon dioxide, methane and water vapour.
Distinguish between the greenhouse effect and the enhanced greenhouse effect.
The greenhouse effect is the natural process that maintains the Earth's mean temperature at around 15°C. The enhanced greenhouse effect is the additional warming caused by increased concentrations of greenhouse gases due to human activity.
Give two sources of carbon dioxide that contribute to the greenhouse effect.
1. The combustion of wood and fossil fuels.\n2. The respiration of plants and animals.\n\nIt is also produced by thermal decomposition of carbonate rocks and by the reaction of acids with carbonates.
True or False?
Methane is released into the atmosphere by the digestive processes of animals.
True.
Methane is produced by the digestive processes of animals, as well as by decomposition of vegetation and bacterial action in swamps and rice paddy fields.
Why are increasing levels of carbon dioxide and methane a concern, even though they are present in only small amounts?
Even in small amounts, carbon dioxide and methane are effective at absorbing and trapping infrared radiation. Rising concentrations are causing the enhanced greenhouse effect, which is leading to global warming and climate change.
Infrared radiation emitted from the Earth's surface is .......... by greenhouse gases, preventing it from escaping into space.
Infrared radiation emitted from the Earth's surface is absorbed by greenhouse gases, preventing it from escaping into space.
Define climate change.
Climate change is a long-term shift in worldwide weather patterns and conditions, largely driven by rising levels of greenhouse gases in the atmosphere.
Explain how burning fossil fuels contributes to climate change.
Burning fossil fuels releases carbon dioxide into the atmosphere. Carbon dioxide is a greenhouse gas that traps heat, leading to the enhanced greenhouse effect and rising global temperatures, which drive climate change.
True or False?
Deforestation increases the amount of carbon dioxide in the atmosphere.
True.
Trees remove CO₂ during photosynthesis. Removing them reduces this uptake, so more CO₂ remains in the atmosphere, enhancing the greenhouse effect.
Increasing agricultural activity and landfill sites contribute to climate change by releasing more .......... into the atmosphere.
Increasing agricultural activity and landfill sites contribute to climate change by releasing more methane into the atmosphere.
Why is historical climate data less reliable than modern measurements?
Historical data was collected without accurate instruments and from fewer locations. Scientists use indirect methods such as ice cores, tree rings and the fossil record to estimate past conditions, but these are less precise than modern techniques.
True or False?
The majority of climate scientists believe that human activity is causing climate change.
True.
Academic surveys show that around 97% of climate scientists agree that human activity is the primary cause of current climate change.
Give two consequences of rising global temperatures caused by climate change.
1. Melting of polar ice caps, leading to higher sea levels.\n2. More frequent and intense droughts that damage crop production. Storms and extreme heat waves are also becoming more common.
Define climate mitigation.
Climate mitigation refers to strategies that adapt to a changing climate rather than preventing it, such as building flood defences, changing crop types and redesigning infrastructure to withstand extreme weather.
Analysis of gas bubbles trapped in .......... allows scientists to estimate past climate conditions.
Analysis of gas bubbles trapped in ice cores allows scientists to estimate past climate conditions.
How does rising sea level threaten coastal areas?
Rising sea levels cause erosion of coastal land, flooding of wetlands and habitat destruction for wildlife. Low-lying cities face increased flooding and permanent loss of land without expensive barrier systems.
Define incomplete combustion.
Incomplete combustion occurs when there is insufficient oxygen for a fuel to burn fully, producing carbon monoxide, soot (carbon particulates) and water instead of carbon dioxide and water.
Why is carbon monoxide particularly dangerous as an atmospheric pollutant?
Carbon monoxide is colourless and odourless, making it impossible to detect without a monitor. It binds to haemoglobin in the blood, preventing it from carrying oxygen, which can cause fainting, coma or death.
True or False?
Sulfur dioxide is produced from the complete combustion of fuels that contain sulfur.
True.\n\nFossil fuels contain small quantities of sulfur. When they burn, the sulfur is oxidised to produce sulfur dioxide, which is a major cause of acid rain.
Sulfur dioxide dissolves in rainwater to form .......... rain, which corrodes metal structures and harms aquatic life.
Sulfur dioxide dissolves in rainwater to form acid rain, which corrodes metal structures and harms aquatic life.
State two problems caused by soot particles released during incomplete combustion.
1. Soot causes respiratory problems by irritating the lungs.\n2. It covers buildings and statues, making them appear dark and dirty, and accelerates corrosion of surfaces.
True or False?
Oxides of nitrogen are produced only from the combustion of fuels that contain nitrogen compounds.
False.
Oxides of nitrogen are produced mainly from vehicle exhausts as a result of the high-temperature reaction between nitrogen and oxygen in the air during combustion — not solely from nitrogen compounds in the fuel.
Name four key pollutant gases produced by the combustion of fossil fuels.
1. Carbon dioxide\n2. Carbon monoxide\n3. Oxides of nitrogen\n4. Oxides of sulfur
Oxides of nitrogen from vehicle exhausts contribute to acid rain and also produce photochemical ...........
Oxides of nitrogen from vehicle exhausts contribute to acid rain and also produce photochemical smog.
Explain why complete combustion is preferred over incomplete combustion in terms of safety and environmental impact.
Complete combustion produces only carbon dioxide and water, whereas incomplete combustion produces poisonous carbon monoxide and soot. Carbon monoxide is toxic and soot causes respiratory and environmental damage, making incomplete combustion more harmful.
What is the main source of atmospheric pollutants?
The main source is the combustion of fossil fuels. Incomplete combustion also produces unburned hydrocarbons and carbon particulates in addition to pollutant gases.
Define potable water.
Potable water is water that has been processed and is safe for human consumption and daily use. It may contain dissolved minerals and salts but must be free of harmful bacteria.
What is the difference between pure water and potable water?
Pure water consists solely of H₂O molecules with no dissolved substances. Potable water may contain dissolved minerals and salts but has been treated to make it safe to drink.
True or False?
Potable water must have a pH between 6.5 and 8.5.
True.\n\nPotable water must meet several standards, including a pH between 6.5 and 8.5, very low levels of dissolved substances, and freedom from harmful bacteria.
Water stored in porous underground rocks is called .......... and the water it holds is known as groundwater.
Water stored in porous underground rocks is called an aquifer and the water it holds is known as groundwater.
Describe the two main steps used to treat fresh water and make it potable.
Filtration removes debris such as soil, grit and small particles using mesh screens followed by sand and gravel beds. Sterilisation then kills bacteria and microbes using chlorine gas, ultraviolet light or ozone.
True or False?
Desalination is a cheap and energy-efficient method for producing potable water on a large scale.
False.\n\nDesalination is an expensive process that consumes large amounts of energy, making it unsuitable as a primary large-scale method. It is used in regions with very hot climates and limited fresh water, such as Saudi Arabia.
Define desalination.
Desalination is the process of removing salt from seawater to produce potable water, carried out by distillation or reverse osmosis using semi-permeable membranes.
How does reverse osmosis produce potable water from seawater?
Seawater is forced through a semi-permeable membrane under pressure. Only water molecules are small enough to pass through the membrane, leaving behind dissolved salts and other ions so that fresh water is collected on the other side.
During water treatment, .......... gas, ultraviolet light or ozone can be used to kill harmful bacteria in the water.
During water treatment, chlorine gas, ultraviolet light or ozone can be used to kill harmful bacteria in the water.
Why does the source of fresh water vary depending on the local climate?
In warmer areas, surface water evaporates before it can be collected, so water is found mainly in underground aquifers. In cooler or wetter regions, surface water from reservoirs, lakes and rivers is more readily available for treatment.

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