Question 1: Explain in your own words what is meant by the term 'early atmosphere' of Earth.

Answer: The early atmosphere of Earth refers to the initially formed gaseous envelope surrounding the planet, primarily composed of gases released from volcanic activity, before the development of a breathable, oxygen-rich atmosphere.

Question 1: Which gases were most abundant in Earth's early atmosphere? List at least three.

Answer: Methane (CH₄), ammonia (NH₃), water vapour (H₂O), carbon dioxide (CO₂), and sulphur dioxide (SO₂).

Question 2: Describe the main process through which the early atmosphere was formed.

Answer: The early atmosphere was formed mainly through volcanic outgassing, which released gases trapped beneath the Earth's crust into the atmosphere.

Question 1: Based on the data provided, how did the proportion of oxygen in the atmosphere change from the early Earth to the present day? (Answer in percentage)

Answer: Oxygen increased from nearly 0% in the early atmosphere to about 21% today.

Question 2: Explain the significance of the increase in oxygen levels during Earth's history.

Answer: The increase in oxygen allowed for the development of aerobic organisms, led to the formation of the ozone layer which protects the Earth from harmful UV radiation, and contributed to the evolution of complex life.

Question 1: Calculate the volume of oxygen in 1000 litres of today's atmosphere, given that oxygen makes up 21% of the atmosphere. (Use the formula: Volume of oxygen = Total volume × percentage of oxygen / 100)

Answer: 210 litres

Question 1: Describe a safe method to simulate volcanic outgassing in a classroom experiment.

Answer: One method is to produce gas mixtures from safe chemicals such as baking soda and vinegar to release carbon dioxide, or using small controlled experiments with inert gases to demonstrate gas release, ensuring proper ventilation and safety equipment are used.

Question 1: Explain how knowledge of Earth's atmospheric evolution can aid in the search for life on other planets.

Answer: Understanding Earth's atmospheric evolution helps scientists identify planets with atmospheres that could support life, by analysing conditions that led to oxygen formation and the development of a protective ozone layer.

Question 2: Discuss one technological advancement that relies on understanding atmospheric composition and its changes over time.

Answer: The development of climate models and remote sensing technologies depends on understanding atmospheric composition and its historical changes, enabling accurate prediction of climate change and monitoring of atmospheric pollutants.