What had the most influence in irreversibly changing the Earth's ...

[futuristic]

What had the most influence in irreversibly changing the Earth's atmosphere?
  a. Formation of carbonic acid in the ocean
  b. Production of oxygen from photosynthesis
  c. Chemical breakup of water vapor by sunlight
  d. Fluctuation in the atmospheric composition

Question 2

Since the formation of our ocean, Earth has made approximately ____ orbits around the galaxy.
  a. 20
  b. 42
  c. 230
  d. 280

[yasmin]

Answer to Question 1

ANS: B
Although all these factors did occur, the addition of oxygen to the atmosphere changed the atmosphere
forever. It was called the oxygen revolution. As more and more photosynthetic organisms evolved,
more oxygen was added into the atmosphere. Information can be found in the section Earth, Ocean,
and Atmosphere Accumulated in Layers Sorted by Density.

Answer to Question 2

ANS: A
The Earth has only made about 20 orbits around the galaxy since the ocean's formation. One orbit
takes approximately 230 million years, despite our speed of 200 kilometers per second. This puts into
perspective the sheer magnitude of our galaxy. Information can be found in the section Stars and Seas.

[futuristic]

Excellent

[kjohnson]

Great answer, keep it coming