Earth Science

Question 1

What % of gases does the Earth’s atmosphere contain?

Answer 1

• 21% Oxygen
• 78% Nitrogen
• 1 % Other gases ( CO2, argon, water vapour)

Question 2

What quantities of gases did the Earth’s early atmosphere contain?

Answer 2

• A large amount of CO2
• Little to no oxygen
• Water vapour
• Small amounts of other gases

Question 3

How did the levels of gases in the Earth’s early atmosphere first change?

Answer 3

While the Earth was forming, volcanoes erupted and released large amounts of water vapour, carbon dioxide, and sulfur dioxide into the atmosphere.
- The water vapour later condensed to form the oceans.

Question 4

How did the levels of gases in the Earth’s early atmosphere change again?

Answer 4

Plants began to develop and photosynthesise - which took the carbon dioxide out of the atmosphere and released oxygen.

Question 5

Explain the greenhouse effect.

Answer 5

The greenhouse gases form a blanket around our Earth.
When the energy from the Sun breaks through these gases, it reflects off of the surface of the Earth; some of this energy will break through the gases, but some will reflect again off of the gases and cause the Earth to warm.
- It also absorbs heat that is radiated from the Earth (like combustion of fuels).