5.2 Quiz: Formation of the Earth

The Earth is estimated to be approximately:

• 4.5 billion years old

• 4.5 million years old

• 45 billion years old

• 45 million years old

Answer explanation

The Earth is estimated to be about 4.5 billion years old, based on radiometric dating of the oldest rocks and meteorites. The other options are significantly lower and incorrect.

Tags

NGSS.MS-ESS1-4

Earth's core is made up of:

• mostly carbon

• nickel and iron

• mostly silicon

• a mix of all elements

Answer explanation

Earth's core is primarily composed of nickel and iron, which are dense metals. This composition is crucial for generating the planet's magnetic field and maintaining its structure, making 'nickel and iron' the correct answer.

When the Earth was young, it was molten do to high amounts of energy and heat from:

• iron forming alloys with nickel

• radioactive elements decaying

• left over heat from the big bang

• left over heat from the supernova explosion

Answer explanation

The Earth was molten due to the decay of radioactive elements, which released significant heat. This process contributed to the high temperatures during the planet's early formation, making it molten.

Tags

NGSS.HS-ESS1-6

Earth's early atmosphere did NOT include which gas?

• N₂

• H₂O

• CO₂

• O₂

Answer explanation

Earth's early atmosphere lacked free oxygen (O2). It primarily consisted of nitrogen (N2), water vapor (H2O), and carbon dioxide (CO2), with O2 being produced later by photosynthetic organisms.

Why is it hard to find very old rocks on Earth?

• Erosion, volcanic eruptions and other processes destroy rocks

• The Earth didn't become solid for billions of years

• The oldest rocks were made into the moon during a collision

• The oldest rocks were destroyed in a huge collision that killed the dinosaurs

Answer explanation

Very old rocks are hard to find because erosion, volcanic eruptions, and other geological processes continuously destroy them. This natural recycling of materials makes it difficult to locate ancient rock formations.

How did the Earth get its moon?

• an impact with a protoplanet that flung debris into space

• it formed at the same time as the Earth from gases

• it was an asteroid that came close enough to begin orbiting Earth

• it was supposed to be a planet but didn't get large enough

Answer explanation

The Earth likely acquired its moon through a giant impact with a protoplanet, which sent debris into orbit around Earth. This debris eventually coalesced to form the moon, making this the most widely accepted theory.

The first particles that formed the Earth were drawn together from:

• electrostatic charges

• gravitational forces

• magnetic forces

• universal forces

Answer explanation

The first particles that formed the Earth were primarily drawn together by electrostatic charges, which allowed atoms to bond and create matter, leading to the formation of the planet.

Tags

NGSS.MS-ESS1-2

NGSS.MS-PS2-4

Once the Earth began to accumulate more mass, which force was responsible for its continued growth?

• electrostatic charges

• gravitational forces

• magnetic forces

• universal forces

Answer explanation

Gravitational forces were responsible for the Earth's continued growth as it accumulated mass. These forces attract matter, allowing the planet to gather more material and increase in size over time.

Tags

NGSS.MS-ESS1-2

NGSS.MS-PS2-4

In the earliest stages of Earth's development, our planet was made of what?

• a very dense core and thick crust

• molten rock

• plasma like our sun

• vast bodies of water

Answer explanation

In the earliest stages of Earth's development, the planet was primarily composed of molten rock due to intense heat from collisions and radioactive decay, which kept the surface in a liquid state.

What happened on the surface of the Earth shortly after it formed?

• The molten rock cooled and formed a crust

• The water on Earth froze solid

• Mountains, volcanoes, and other land forms were created

• The atmosphere began to form

Answer explanation

Shortly after Earth formed, the intense heat caused by its formation led to molten rock on the surface. As it cooled, this molten rock solidified to form a crust, which is the correct answer.

Tags

NGSS.HS-ESS1-6