Early Earth

Scientists know that Earth and Moon formed in the same part of the solar system because they have

• nearly the same ration of rock to metal
• experienced about the same number of asteroid impacts.
• the same oxygen isotope ratio
• the same ratio of oxygen to other atmospheric gases.

Earth's first crust was probably make of

• anorthosite
• granite
• basalt
• ultramafic peridotite

The densest part of the plant Earth is the

• core
• mantle
• continental crust
• oceanic crus

The Sun formed

• several hundred million years before the planets
• about 100,000 years before the plants
• at around the same time as the planets
• not long after the planets

Early Earth was intensely hot because of 

• short-lived radioactive decay
• intense bombardment from asteriod impacts
• contraction of materials due to gravity
• all of these

Earth seperated into layers based on

• gravity
• metallicity
• the tendency for material to recycle
• density

For a planet it's size, Earth

• has a faster spin
• is rounder
• has a smaller core
• has a high oxygen isotope ratio

Gases in the first atmosphere came from

• asteriod impacts
• comet impacts
• volcanic outgassing
• all of these

Scientists know that Earth had an ocean by 4 billion years ago because 

• fossil fish are found in rocks of that age
• marine sedimentary rocks of that age can be dated
• high tide lines are found around the basin of the ancient ocean
• there was water and basins so there must have been oceans

Due to Earth's large size, it did not experience intense bombardment from asteroid impacts.

• true
• false