How the Earth Formed

Approximately what percentage of the Earth's surface is covered with water?

• 25%
• 60%
• 75%
• 90%

Tags

NGSS.MS-ESS2-4

What happened to Earth as gravity crushed the rock at its center?

• a. It formed an irregular shape.
• b. It became round.
• c. The moon formed.
• d. It rotated faster.

Choose two things that caused the Earth to become warmer as it formed:

• a. gases fusing in the center of the Earth
• b. radioactive materials present at the time of formation
• c. energy from planetesimals crashing into the Earth
• d. the speed of the Earth's rotation

Tags

NGSS.HS-ESS1-6

As Earth’s rocks melted, denser materials sank to Earth’s center to form the

• a. crust
• b. mantle
• c. core

Less dense materials floated to Earth’s surface to form the

• a. crust
• b. mantle
• c. core

The layer of Earth beneath the crust is called the

• a. crust
• b. mantle
• c. core

Most of Earth’s atmosphere TODAY is made up of

• a. carbon dioxide and helium.
• b. nitrogen and helium.
• c. carbon dioxide and oxygen.
• d. nitrogen and oxygen.

Scientists believe that Earth’s EARLY atmosphere was a mixture of carbon dioxide and

• a. water vapor.
• b. helium.
• c. oxygen.
• d. dust particles.

As Earth’s early atmosphere changed, it probably formed from

• a. meteoroids.
• b. hot springs.
• c. crystal rock.
• d. volcanic gases.

True or False: Some of the water in Earth's oceans may have come from water vapor released by volcanoes.

• True
• False