Earth's atmosphere

Learn it by playing

Answer these questions to earn energy, then fish and explore. No account needed.

For teachers: ready-to-use lesson slides, revision notes, diagrams for Earth's atmosphere (KS3 Science, Chemistry) — use them in your lesson, or run the topic as an interactive class activity your students play as a live game.

Lesson notes

Composition of Earth's Atmosphere

**Nitrogen** is the most abundant gas, making up **78%** of the atmosphere.
**Oxygen** is the second most abundant at **21%**.
**Argon** accounts for **0.9%**.
**Carbon dioxide** is present at **0.04%**, along with small amounts of other gases.

Early Atmosphere

Earth formed about **4.5 billion years ago** with intense volcanic activity.
The early atmosphere consisted mostly of **carbon dioxide** and some **water vapour**.
As Earth cooled, water vapour **condensed** to form oceans.

Role of Cyanobacteria

**Cyanobacteria** were single-celled organisms that carried out **photosynthesis**.
Photosynthesis uses carbon dioxide and water to produce **glucose** and **oxygen**.
Cyanobacteria were responsible for producing **oxygen** in the atmosphere.

Greenhouse Gases and Global Warming

**Carbon dioxide** is a **greenhouse gas** that contributes to **global warming**.
Greenhouse gases reflect some **infra-red radiation** back to Earth, raising the average temperature.
Burning **fossil fuels** (coal, oil, gas) increases atmospheric carbon dioxide.
Effects of global warming include **extreme weather**, **melting polar ice caps**, and **flooding** of low-lying areas.

Particle arrangement in solids, liquids, and gases. The atmosphere is a mixture of gases with particles far apart and moving rapidly.

Slides

Step through every slide for this topic — plus flashcards and revision notes — with a free account.

Practice questions

Free preview — 8 of 40 questions. Sign up to see them all.

1.Which gas is the most abundant in Earth's atmosphere?
Easy
- ANitrogen
- BOxygen
- CArgon
- DCarbon dioxide
2.What percentage of Earth's atmosphere is oxygen?
Easy
- A78%
- B21%
- C0.9%
- D0.04%
3.Earth's early atmosphere consisted mostly of which gas?
Medium
- ANitrogen
- BOxygen
- CCarbon dioxide
- DArgon
4.Which organism was responsible for producing oxygen in Earth's early atmosphere?
Medium
- ACyanobacteria
- BPlants
- CAlgae
- DAnimals
5.How do greenhouse gases cause global warming?
Medium
- AThey absorb all incoming solar radiation.
- BThey reflect infra-red radiation back to Earth.
- CThey prevent oxygen from entering the atmosphere.
- DThey increase the amount of water vapour.
6.What is global warming?
Easy
- AA decrease in Earth's average temperature.
- BAn increase in Earth's average temperature.
- CAn increase in the amount of oxygen in the atmosphere.
- DA decrease in the amount of carbon dioxide.
7.Burning fossil fuels increases the amount of which gas in the atmosphere?
Easy
- ANitrogen
- BOxygen
- CCarbon dioxide
- DArgon
8.Which of the following is NOT a fossil fuel?
Easy
- AOil
- BCoal
- CNatural gas
- DWood

More questions

9.Which of the following is an effect of global warming?
Medium
- AMore extreme weather events
- BDecrease in sea levels
- CReduced melting of polar ice caps
- DCooling of the Earth
10.Venus has an atmosphere mostly of carbon dioxide. What effect does this have on its average temperature?
Medium
- AIt makes Venus cooler than Earth.
- BIt makes Venus warmer than Earth.
- CIt has no effect on temperature.
- DIt makes Venus the same temperature as Earth.
11.How does deforestation affect carbon dioxide levels in the atmosphere?
Hard
- AIt decreases carbon dioxide levels because trees release CO2.
- BIt increases carbon dioxide levels because fewer trees absorb CO2.
- CIt has no effect on carbon dioxide levels.
- DIt decreases carbon dioxide levels because deforested land absorbs more CO2.
12.What process did cyanobacteria use to produce oxygen?
Medium
- ARespiration
- BPhotosynthesis
- CCombustion
- DDecomposition
13.The pie chart of Earth's atmosphere shows nitrogen at 78%, oxygen at 21%, and argon at 0.9%. If a sample of air contains 1000 molecules, approximately how many molecules of oxygen would it contain?
Medium
- A210
- B780
- C9
- D21
14.A student measures the composition of a gas sample and finds it contains 78% nitrogen, 21% oxygen, and 1% other gases. Which gas is most likely missing from the measured composition according to the typical composition of Earth's atmosphere?
Medium
- AArgon
- BCarbon dioxide
- CWater vapour
- DHelium
15.Earth's early atmosphere, produced by volcanic activity, consisted mostly of carbon dioxide and water vapour. As the Earth cooled, water vapour condensed to form oceans. This process removed water vapour from the atmosphere. What effect would this have on the total atmospheric pressure?
Hard
- AIt would decrease.
- BIt would increase.
- CIt would stay the same.
- DIt would initially increase then decrease.
16.Cyanobacteria carried out photosynthesis, which uses carbon dioxide and water to produce glucose and oxygen. If cyanobacteria produced 1000 kg of glucose, approximately how much oxygen would be produced? (Relative formula masses: CO2 = 44, H2O = 18, C6H12O6 = 180, O2 = 32)
Medium
- A1067 kg
- B533 kg
- C1600 kg
- D800 kg
17.The table shows the percentage of carbon dioxide in the atmosphere over time. Year 1800: 0.028%, Year 1900: 0.030%, Year 2000: 0.037%, Year 2020: 0.041%. Which statement is correct?
Medium
- AThe concentration of carbon dioxide has increased by about 50% from 1800 to 2020.
- BThe concentration of carbon dioxide has doubled from 1800 to 2020.
- CThe concentration of carbon dioxide has remained constant.
- DThe concentration of carbon dioxide increased by 0.013% between 1800 and 2000.
18.Burning fossil fuels increases atmospheric carbon dioxide. If a power plant burns coal that is 80% carbon by mass, how much carbon dioxide is produced from 1000 kg of coal? (Atomic masses: C=12, O=16)
Medium
- A2933 kg
- B800 kg
- C1000 kg
- D1467 kg
19.The graph shows global average temperature from 1880 to 2020. The temperature in 1880 was 13.7°C and in 2020 it was 14.9°C. What is the increase in temperature?
Easy
- A1.2°C
- B0.8°C
- C1.5°C
- D2.0°C
20.Venus has an atmosphere that is mostly carbon dioxide, leading to a very high surface temperature. Earth's atmosphere contains about 0.04% carbon dioxide. If Earth's carbon dioxide level rose to 1%, which effect would be most likely?
Hard
- AIncreased global warming due to more infrared radiation being trapped.
- BDecreased global warming because more carbon dioxide blocks sunlight.
- CNo change because carbon dioxide is only a small fraction.
- DIncreased oxygen levels because plants would photosynthesise more.
21.Deforestation reduces the number of trees. Which statement best explains how this affects atmospheric carbon dioxide levels?
Medium
- AFewer trees means less photosynthesis, so less carbon dioxide is removed from the atmosphere.
- BFewer trees means less respiration, so less carbon dioxide is released.
- CDeforestation releases carbon dioxide directly from burning trees.
- DTrees absorb oxygen, so deforestation increases oxygen levels.
22.Which two gases together make up 99% of Earth's atmosphere?
Easy
- ANitrogen and oxygen
- BOxygen and argon
- CNitrogen and carbon dioxide
- DOxygen and carbon dioxide
23.A student investigates the greenhouse effect using two beakers, one covered with plastic wrap and one uncovered, both under a lamp. The temperature is measured every 5 minutes. Which beaker is expected to show a higher temperature after 20 minutes?
Medium
- AThe beaker covered with plastic wrap, because it traps infrared radiation.
- BThe uncovered beaker, because it allows more light in.
- CBoth beakers will have the same temperature.
- DThe covered beaker will be cooler because plastic reflects light.
24.A factory releases 500 tonnes of carbon dioxide per year. A forest of 10,000 trees absorbs 250 tonnes of carbon dioxide per year. How many additional trees need to be planted to offset the factory's emissions completely?
Hard
- A20,000
- B10,000
- C30,000
- D5,000
25.A student heats a sample of air over a hot copper coil to remove oxygen. After cooling, the volume of gas remaining is 79 cm³ from an initial 100 cm³. What is the approximate percentage of oxygen in the air sample?
Medium
- A21%
- B79%
- C50%
- D100%
26.In an experiment to measure the percentage of oxygen in air, a student uses a gas syringe containing 100 cm³ of air and passes it repeatedly over heated copper powder. After several passes, the volume reads 79 cm³. Which gas is removed by the hot copper?
Medium
- ANitrogen
- BOxygen
- CCarbon dioxide
- DArgon
27.Which of the following processes produces oxygen in Earth's atmosphere?
Easy
- ARespiration
- BPhotosynthesis
- CCombustion
- DVolcanic activity
28.Earth's early atmosphere, produced by volcanic activity, consisted mostly of carbon dioxide and water vapour. As the Earth cooled, water vapour condensed to form oceans. What happened to most of the carbon dioxide?
Medium
- AIt was used by cyanobacteria in photosynthesis
- BIt dissolved into the oceans and formed carbonate rocks
- CIt was removed by burning fossil fuels
- DIt escaped into space
29.A student investigates the greenhouse effect using two beakers, each containing 100 cm³ of water at 20°C. Beaker A is covered with plastic wrap. Both beakers are placed under a lamp for 30 minutes. The temperature of water in beaker A rises to 35°C, and in beaker B to 28°C. Which statement best explains the difference?
Medium
- AThe plastic wrap reflects sunlight, reducing heating in beaker A
- BThe plastic wrap traps heat, preventing it from escaping, so beaker A gets hotter
- CBeaker B has more water, so it heats up more slowly
- DThe lamp is closer to beaker A
30.A factory releases 500 tonnes of carbon dioxide per year. A forest of 10,000 trees absorbs 250 tonnes of carbon dioxide per year. How many additional trees need to be planted to make the factory carbon-neutral?
Medium
- A10,000 trees
- B20,000 trees
- C30,000 trees
- D40,000 trees
31.The graph shows the concentration of atmospheric carbon dioxide in parts per million (ppm) from 1800 to 2020. In 1800 it was 280 ppm, in 1900 it was 300 ppm, and in 2000 it was 370 ppm. Which statement best describes the trend?
Hard
- AThe concentration increased at a constant rate
- BThe concentration increased, and the rate of increase became faster over time
- CThe concentration increased, then decreased
- DThe concentration remained constant
32.A student uses the apparatus shown to measure the percentage of oxygen in air. The apparatus consists of a gas syringe connected to a tube containing copper wool, which is heated. The student records the initial volume of air as 50 cm³. After passing the air back and forth over the hot copper several times, the final volume is 39.5 cm³. What is the percentage of oxygen in the air?
Hard
- A21%
- B10.5%
- C26.6%
- D79%
33.Which of the following is a method to reduce the amount of carbon dioxide in the atmosphere?
Medium
- ABurning more fossil fuels
- BDeforestation
- CPlanting more trees
- DIncreasing the number of cars
34.Venus has an atmosphere that is mostly carbon dioxide. Earth's atmosphere contains about 0.04% carbon dioxide. If Earth had as much carbon dioxide as Venus, what would be the most likely effect on Earth's average temperature?
Hard
- AIt would decrease because carbon dioxide blocks sunlight
- BIt would increase significantly due to a stronger greenhouse effect
- CIt would remain the same because carbon dioxide does not affect temperature
- DIt would decrease because plants would absorb more carbon dioxide
35.In an experiment to demonstrate the greenhouse effect, two thermometers are placed in separate glass jars. One jar is filled with air, the other with carbon dioxide. Both are exposed to a heat lamp. Which thermometer will show a higher temperature after 10 minutes?
Medium
- AThe one in air
- BThe one in carbon dioxide
- CBoth will be the same
- DNeither will change
36.What is the percentage of argon in Earth's atmosphere?
Easy
- A0.9%
- B0.04%
- C21%
- D78%
37.What is the percentage of carbon dioxide in Earth's atmosphere?
Easy
- A0.04%
- B0.9%
- C21%
- D78%
38.Earth's early atmosphere was produced mainly by volcanic activity. Which gas was most abundant in this early atmosphere?
Medium
- ACarbon dioxide
- BOxygen
- CNitrogen
- DArgon
39.What process did cyanobacteria use to produce oxygen in Earth's early atmosphere?
Medium
- APhotosynthesis
- BRespiration
- CCombustion
- DVolcanic activity
40.Which of the following is a greenhouse gas?
Medium
- ACarbon dioxide
- BNitrogen
- COxygen
- DArgon

Revision notes

## Earth's Atmosphere - **Current composition**: Nitrogen (78%), Oxygen (21%), Argon (0.9%), Carbon dioxide (0.04%), and other gases. - **Most abundant gas**: Nitrogen. ### Early Atmosphere - Formed ~4.5 billion years ago. - Mostly carbon dioxide and water vapour from volcanic activity. - As Earth cooled, water vapour condensed to form oceans. ### Change due to Cyanobacteria - Cyanobacteria performed **photosynthesis**: - carbon dioxide + water → (light) → glucose + oxygen. - This produced oxygen, changing the atmosphere. ### Greenhouse Gases & Global Warming - Carbon dioxide is a **greenhouse gas**. - **Global warming**: raising of Earth's average temperature. - How it works: 1. Thermal (infra-red) radiation reaches Earth from the Sun. 2. Earth absorbs and re-emits some infra-red radiation. 3. Greenhouse gases reflect some of this back to Earth. - This raises the average temperature. ### Human Impact - Burning fossil fuels (oil, coal, gas) increases carbon dioxide levels. - Effects of global warming: - More extreme weather events. - Melting of polar ice caps. - Flooding of low-lying countries. ### Key Points - Photosynthesis by cyanobacteria added oxygen. - Deforestation increases CO₂; planting trees reduces it (trees absorb CO₂ via photosynthesis). - Venus has a CO₂-rich atmosphere, causing a very high average temperature.

Nitrogen: The most abundant gas in Earth's atmosphere, accounting for 78%.
Oxygen: The second most abundant gas in Earth's atmosphere, at 21%.
Argon: The third most abundant gas in Earth's atmosphere, at 0.9%.
Carbon dioxide: A greenhouse gas present at 0.04% in the atmosphere; increased by burning fossil fuels.
Cyanobacteria: Single-celled organisms that carried out photosynthesis, producing oxygen and changing the atmosphere.
Photosynthesis: Process where carbon dioxide and water, in the presence of light, produce glucose and oxygen.
Greenhouse gas: A gas (e.g., carbon dioxide) that reflects infra-red radiation back to Earth, causing global warming.
Global warming: The raising of the average temperature of Earth due to greenhouse gases.
Fossil fuels: Fuels like oil, coal, and gas; burning them increases atmospheric carbon dioxide.

Flashcards

What is the most abundant gas in Earth's atmosphere?

Nitrogen, which accounts for 78% of the atmosphere.

What percentage of Earth's atmosphere is oxygen?

Oxygen makes up 21% of Earth's atmosphere.

What is the third most abundant gas in Earth's atmosphere?

Argon, at 0.9%.

What percentage of Earth's atmosphere is carbon dioxide?

Carbon dioxide is present at 0.04%.

What was the composition of Earth's early atmosphere?

It consisted mostly of carbon dioxide and a smaller amount of water vapour.

What caused the early atmosphere to change from mostly carbon dioxide?

Intense volcanic activity initially produced the atmosphere; later, cyanobacteria carried out photosynthesis, producing oxygen.

What are cyanobacteria?

Single-celled organisms that carried out photosynthesis, producing oxygen and changing Earth's atmosphere.

What is the chemical equation for photosynthesis?

Carbon dioxide + water → glucose + oxygen (in the presence of light).

What is a greenhouse gas?

A gas that contributes to global warming by reflecting infra-red radiation back to Earth.

How do greenhouse gases cause global warming?

They reflect some infra-red radiation back to Earth, raising the average temperature.

What is global warming?

A raising of the average temperature of Earth.

What effect does burning fossil fuels have on carbon dioxide levels?

It increases the amount of carbon dioxide in the atmosphere.

Name three fossil fuels.

Oil, coal, and gas.

What are two effects of global warming?

More extreme weather events and melting of polar ice caps, which can cause flooding of low-lying countries.

How did Earth's oceans form?

As Earth cooled, water vapour in the early atmosphere condensed to form oceans.

What is the role of photosynthesis in Earth's atmosphere?

It produced oxygen, changing the composition of the atmosphere.

What is the source of thermal radiation that reaches Earth?

The Sun.

What happens to infra-red radiation after Earth absorbs and re-emits it?

Greenhouse gases reflect some of it back to Earth.

Why is carbon dioxide considered a greenhouse gas?

It reflects infra-red radiation back to Earth, contributing to global warming.

What was the initial source of Earth's early atmosphere?

Intense volcanic activity.

How old is Earth?

Earth was formed around 4.5 billion years ago.

What is the approximate percentage of argon in Earth's atmosphere?

0.9%.

Unlock all 40 questions, flashcards & more

Create a free account to see every question, the slides, flashcards and revision notes for this topic.

Past papers

Past-paper practice for this topic is coming soon.

Coming soon