The atmosphere

Question 1

What are the main gases in the Earth’s atmosphere and their approximate percentages?

Answer 1

nitrogen = 71%
Oxygen = 21%
argon and other noble gases = 1% or less
carbon dioxide = 0.04%

Question 2

Why is the amount of carbon dioxide in the atmosphere important?

Answer 2

It helps regulate Earth’s temperature and is a key factor in climate change.

Question 3

What was the composition of Earth’s early atmosphere, and how did it form?

Answer 3

The early atmosphere was formed by volcanic activity and consisted mainly of carbon dioxide, water vapor, and small amounts of ammonia and methane.

Question 4

How did oxygen levels in the atmosphere increase over time?

Answer 4

Photosynthetic organisms (e.g., cyanobacteria) evolved and released oxygen as a byproduct.

Question 5

Name three greenhouse gases and explain how they contribute to global warming.

Answer 5

Carbon dioxide, methane,
and water vapor. These gases trap heat in the atmosphere by absorbing infrared radiation, preventing it from escaping into space.

Question 6

What are two human activities that increase the levels of carbon dioxide and methane?

Answer 6

Carbon dioxide: Burning fossil fuels and deforestation.
Methane: Agriculture (e.g., cattle farming) and landfill waste.

Question 7

What environmental problems are caused by sulfur dioxide and nitrogen oxides?

Answer 7

They dissolve in rainwater to form acid rain, which damages buildings, kills plants, and harms aquatic life.

Question 8

What is the main risk of carbon monoxide to human health?

Answer 8

It binds to hemoglobin in the blood, preventing oxygen transport, which can lead to poisoning and death.